问题

You are supposed to provide a solution to a given problem.

Problem:
Let f be a bounded entire function, z_1,z_2 be two points in the ball B(0,r). What is the value of the integral $\int_{|z|=r} f(z)/(z-z_1)(z-z_2) dz$?
Solution:

答案

模型 模型答案 正确答案
金声玉亮2.0 The solution to this problem can be found using the Cauchy Integral Formula and the concept of residues in complex analysis. Given that \( f \) is a bounded entire function, it is analytic everywhere in the complex plane. Let \( z_1, z_2 \in B(0, r) \), meaning that \( |z_1| < r \) and \( |z_2| < r \). We are interested in evaluating the integral

\[
\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz.
\]

Since \( f \) is analytic and bounded, the function \( \frac{f(z)}{(z-z_1)(z-z_2)} \) has simple poles at \( z_1 \) and \( z_2 \). According to the Residue Theorem, the integral of a function around a closed contour is equal to \( 2\pi i \) times the sum of the residues of the function at the poles inside the contour. Here, both \( z_1 \) and \( z_2 \) are inside the contour \( |z|=r \).

The residue of \( \frac{f(z)}{(z-z_1)(z-z_2)} \) at \( z_1 \) can be computed as

\[
\text{Res}_{z=z_1} \left(\frac{f(z)}{(z-z_1)(z-z_2)}\right) = \lim_{z\to z_1} (z-z_1) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_1)}{z_1-z_2}.
\]

Similarly, the residue at \( z_2 \) is

\[
\text{Res}_{z=z_2} \left(\frac{f(z)}{(z-z_1)(z-z_2)}\right) = \lim_{z\to z_2} (z-z_2) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_2)}{z_2-z_1}.
\]

Therefore, by the Residue Theorem, the integral is

\[
\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i \left( \frac{f(z_1)}{z_1-z_2} + \frac{f(z_2)}{z_2-z_1} \right) = 2\pi i \left( \frac{f(z_1) - f(z_2)}{z_1-z_2} \right).
\]

This result provides the value of the integral in terms of the function values at \( z_1 \) and \( z_2 \) and their difference.
0.0
deepseekr1

The integral evaluates to **0**.

**Step-by-Step Explanation:**

1. **Liouville's Theorem:** Since \( f \) is a bounded entire function, by Liouville's theorem, \( f \) must be constant. Let \( f(z) = C \) where \( C \) is a constant.

2. **Simplify the Integral:** The integral becomes:
\[
C \int_{|z|=r} \frac{1}{(z - z_1)(z - z_2)} \, dz
\]

3. **Partial Fraction Decomposition:**
\[
\frac{1}{(z - z_1)(z - z_2)} = \frac{1}{z_1 - z_2} \left( \frac{1}{z - z_1} - \frac{1}{z - z_2} \right)
\]

4. **Integrate Each Term:**
\[
\frac{C}{z_1 - z_2} \left( \int_{|z|=r} \frac{1}{z - z_1} \, dz - \int_{|z|=r} \frac{1}{z - z_2} \, dz \right)
\]
By Cauchy's Integral Formula, each integral equals \( 2\pi i \), resulting in:
\[
\frac{C}{z_1 - z_2} (2\pi i - 2\pi i) = 0
\]

5. **Residue Theorem Approach:** Alternatively, compute residues at \( z_1 \) and \( z_2 \):
- Residue at \( z_1 \): \( \frac{C}{z_1 - z_2} \)
- Residue at \( z_2 \): \( \frac{C}{z_2 - z_1} \)
Summing residues gives \( 0 \), so the integral is \( 2\pi i \times 0 = 0 \).

**Conclusion:** The integral equals **0** regardless of the specific points \( z_1, z_2 \) inside the ball, as the contributions from each pole cancel out due to \( f \) being constant.
0.0
gpto1 To solve the problem, we are asked to evaluate the integral
\[
I = \int_{|z|=r} \frac{f(z)}{(z - z_1)(z - z_2)} \, dz
\]
where \( f \) is a bounded entire function, and \( z_1, z_2 \) are two points inside the circle \( |z|=r \).

**Step 1: Recognize that \( f \) is constant**

Since \( f \) is an entire (analytic everywhere in the complex plane) and bounded function, Liouville's Theorem tells us that \( f \) must be constant. That is,
\[
f(z) = c
\]
for some constant \( c \).

**Step 2: Simplify the integral**

Substituting \( f(z) = c \) into the integral, we have
\[
I = c \int_{|z|=r} \frac{1}{(z - z_1)(z - z_2)} \, dz
\]

**Step 3: Compute the integral using the Residue Theorem**

The integrand has simple poles at \( z = z_1 \) and \( z = z_2 \), both inside the circle \( |z|=r \). By the Residue Theorem,
\[
I = 2\pi i \times \left( \operatorname{Res}_{z=z_1} \frac{1}{(z - z_1)(z - z_2)} + \operatorname{Res}_{z=z_2} \frac{1}{(z - z_1)(z - z_2)} \right)
\]

**Computing the residues:**

- At \( z = z_1 \):
\[
\operatorname{Res}_{z=z_1} \frac{1}{(z - z_1)(z - z_2)} = \lim_{z \to z_1} (z - z_1) \frac{1}{(z - z_1)(z - z_2)} = \frac{1}{z_1 - z_2}
\]

- At \( z = z_2 \):
\[
\operatorname{Res}_{z=z_2} \frac{1}{(z - z_1)(z - z_2)} = \lim_{z \to z_2} (z - z_2) \frac{1}{(z - z_1)(z - z_2)} = \frac{1}{z_2 - z_1} = -\frac{1}{z_1 - z_2}
\]

**Step 4: Sum of the residues**

Adding the residues:
\[
\operatorname{Res}_{z=z_1} + \operatorname{Res}_{z=z_2} = \frac{1}{z_1 - z_2} - \frac{1}{z_1 - z_2} = 0
\]

**Step 5: Evaluate the integral**

Since the sum of the residues is zero:
\[
I = 2\pi i \times 0 = 0
\]

Thus, the value of the original integral is zero.

**Answer:**
0
0.0
GPT-4o To solve the problem of finding the value of the integral \(\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} \, dz\), we will apply the **Residue Theorem** from complex analysis. The Residue Theorem is particularly useful for evaluating integrals of meromorphic functions over closed contours.

Given:
- \( f \) is a bounded entire function.
- \( z_1 \) and \( z_2 \) are points inside the ball \( B(0, r) \), i.e., \( |z_1| < r \) and \( |z_2| < r \).

First, recall the Residue Theorem, which states that if \( g(z) \) is a meromorphic function inside and on a simple closed contour \( C \), then:

\[
\int_C g(z) \, dz = 2\pi i \sum \text{Res}(g, a_k)
\]

where the sum is over all residues of \( g \) inside \( C \).

In our case, the function to integrate is:

\[
g(z) = \frac{f(z)}{(z-z_1)(z-z_2)}
\]

The function \( g(z) \) has simple poles at \( z = z_1 \) and \( z = z_2 \). Since \( f(z) \) is entire (analytic everywhere) and bounded, it does not introduce any additional poles.

To apply the Residue Theorem, we need to calculate the residues of \( g(z) \) at \( z = z_1 \) and \( z = z_2 \).

1. **Residue at \( z = z_1 \)**:
\[
\text{Res}(g, z_1) = \lim_{z \to z_1} (z - z_1) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_1)}{z_1 - z_2}
\]

2. **Residue at \( z = z_2 \)**:
\[
\text{Res}(g, z_2) = \lim_{z \to z_2} (z - z_2) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_2)}{z_2 - z_1}
\]

Now, applying the Residue Theorem to the contour \(|z| = r\):

\[
\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} \, dz = 2\pi i \left( \text{Res}(g, z_1) + \text{Res}(g, z_2) \right)
\]

Substituting the residues we found:

\[
\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} \, dz = 2\pi i \left( \frac{f(z_1)}{z_1 - z_2} + \frac{f(z_2)}{z_2 - z_1} \right)
\]

Notice that:

\[
\frac{f(z_1)}{z_1 - z_2} + \frac{f(z_2)}{z_2 - z_1} = \frac{f(z_1)}{z_1 - z_2} - \frac{f(z_2)}{z_1 - z_2} = \frac{f(z_1) - f(z_2)}{z_1 - z_2}
\]

Therefore:

\[
\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} \, dz = 2\pi i \cdot \frac{f(z_1) - f(z_2)}{z_1 - z_2}
\]

So, the value of the integral is:

\[
\boxed{2\pi i \cdot \frac{f(z_1) - f(z_2)}{z_1 - z_2}}
\]
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llama3.1-70B-Instruct

A nice problem in complex analysis!

Since $f$ is a bounded entire function, it is analytic everywhere in the complex plane. We are given two points $z_1$ and $z_2$ inside the ball $B(0,r)$, which means $|z_1| < r$ and $|z_2| < r$.

We want to evaluate the integral $\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz$.

Using the Cauchy Integral Formula, we can write:

$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = \int_{|z|=r} \frac{f(z)}{z-z_1} \cdot \frac{1}{z-z_2} dz$$

Now, we can use the fact that $f$ is analytic and bounded to apply the Cauchy Integral Formula to the first factor:

$$\int_{|z|=r} \frac{f(z)}{z-z_1} dz = 2\pi i f(z_1)$$

So, we are left with:

$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i f(z_1) \int_{|z|=r} \frac{1}{z-z_2} dz$$

Now, we can use the fact that the integral of $\frac{1}{z-z_2}$ around a circle centered at $z_2$ is equal to $2\pi i$ if the circle is traversed in the positive direction (which is the case here, since $|z|=r$ is a circle centered at the origin). Therefore:

$$\int_{|z|=r} \frac{1}{z-z_2} dz = 2\pi i$$

Putting everything together, we get:

$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i f(z_1) \cdot 2\pi i = 4\pi^2 i f(z_1)$$

So, the value of the integral is $4\pi^2 i f(z_1)$.
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llama3.1-405B-Instruct

To evaluate the integral $\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz$, we can use the Cauchy Integral Formula.

The Cauchy Integral Formula states that if $f$ is analytic in a simply connected domain $D$ and $z_0$ is a point in $D$, then for any simple closed curve $\gamma$ in $D$ that encloses $z_0$, we have:

$$f(z_0) = \frac{1}{2\pi i} \int_\gamma \frac{f(z)}{z-z_0} dz$$

In this case, we have two points $z_1$ and $z_2$ in the ball $B(0,r)$, and we want to evaluate the integral $\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz$.

We can rewrite the integral as:

$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = \int_{|z|=r} \frac{f(z)}{z-z_1} \cdot \frac{1}{z-z_2} dz$$

Now, we can apply the Cauchy Integral Formula to the first factor:

$$\int_{|z|=r} \frac{f(z)}{z-z_1} dz = 2\pi i f(z_1)$$

So, we have:

$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i f(z_1) \cdot \frac{1}{z_1-z_2}$$

Similarly, we can apply the Cauchy Integral Formula to the second factor:

$$\int_{|z|=r} \frac{f(z)}{z-z_2} dz = 2\pi i f(z_2)$$

So, we have:

$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i f(z_2) \cdot \frac{1}{z_2-z_1}$$

Since $z_1$ and $z_2$ are in the ball $B(0,r)$, we have $|z_1| < r$ and $|z_2| < r$. Therefore, the integrals $\int_{|z|=r} \frac{f(z)}{z-z_1} dz$ and $\int_{|z|=r} \frac{f(z)}{z-z_2} dz$ are both equal to $2\pi i f(z_1)$ and $2\pi i f(z_2)$, respectively.

Hence, we have:

$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i \left( \frac{f(z_1)}{z_1-z_2} - \frac{f(z_2)}{z_1-z_2} \right)$$

Simplifying, we get:

$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i \left( \frac{f(z_1)-f(z_2)}{z_1-z_2} \right)$$

This is the final answer.
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DeepSeek-Coder-V2 To solve the given problem, we will use Cauchy's integral formula and its extensions. Here is the step-by-step solution:

1. **Identify the function and the contour**:
- The function \( f \) is a bounded entire function.
- The contour is the circle \( |z| = r \).
- The integrand is \( \frac{f(z)}{(z-z_1)(z-z_2)} \).

2. **Apply the residue theorem**:
- The integrand has two simple poles at \( z = z_1 \) and \( z = z_2 \).
- We need to find the residues at these poles.

3. **Calculate the residue at \( z = z_1 \)**:
- The residue at \( z = z_1 \) is given by:
\[
\text{Res}\left(\frac{f(z)}{(z-z_1)(z-z_2)}, z_1\right) = \lim_{z \to z_1} (z-z_1) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_1)}{z_1 - z_2}
\]

4. **Calculate the residue at \( z = z_2 \)**:
- The residue at \( z = z_2 \) is given by:
\[
\text{Res}\left(\frac{f(z)}{(z-z_1)(z-z_2)}, z_2\right) = \lim_{z \to z_2} (z-z_2) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_2)}{z_2 - z_1}
\]

5. **Sum the residues**:
- The sum of the residues is:
\[
\frac{f(z_1)}{z_1 - z_2} + \frac{f(z_2)}{z_2 - z_1} = \frac{f(z_1)}{z_1 - z_2} - \frac{f(z_2)}{z_1 - z_2} = \frac{f(z_1) - f(z_2)}{z_1 - z_2}
\]

6. **Apply the residue theorem**:
- By the residue theorem, the integral is equal to \( 2\pi i \) times the sum of the residues:
\[
\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} \, dz = 2\pi i \left( \frac{f(z_1) - f(z_2)}{z_1 - z_2} \right)
\]

Therefore, the value of the integral is:
\[
\boxed{2\pi i \left( \frac{f(z_1) - f(z_2)}{z_1 - z_2} \right)}
\]
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Qwen2-72B-Instruct The solution to this problem can be found using the Cauchy Integral Formula and the concept of residues in complex analysis. Given that $f$ is a bounded entire function, it is analytic everywhere in the complex plane. Let $z_1, z_2 \in B(0, r)$, meaning that $|z_1| < r$ and $|z_2| < r$. We are interested in evaluating the integral

\[
\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz.
\]

Since $f$ is analytic and bounded, the function $\frac{f(z)}{(z-z_1)(z-z_2)}$ has simple poles at $z_1$ and $z_2$. According to the Residue Theorem, the integral of a function around a closed contour is equal to $2\pi i$ times the sum of the residues of the function at the poles inside the contour. Here, both $z_1$ and $z_2$ are inside the contour $|z|=r$.

The residue of $\frac{f(z)}{(z-z_1)(z-z_2)}$ at $z_1$ can be computed as

\[
\text{Res}_{z=z_1} \left(\frac{f(z)}{(z-z_1)(z-z_2)}\right) = \lim_{z\to z_1} (z-z_1) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_1)}{z_1-z_2}.
\]

Similarly, the residue at $z_2$ is

\[
\text{Res}_{z=z_2} \left(\frac{f(z)}{(z-z_1)(z-z_2)}\right) = \lim_{z\to z_2} (z-z_2) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_2)}{z_2-z_1}.
\]

Therefore, by the Residue Theorem, the integral is

\[
\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i \left( \frac{f(z_1)}{z_1-z_2} + \frac{f(z_2)}{z_2-z_1} \right) = 2\pi i \left( \frac{f(z_1) - f(z_2)}{z_1-z_2} \right).
\]

This result provides the value of the integral in terms of the function values at $z_1$ and $z_2$ and their difference.
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baichuan4 To solve this problem, we can use the residue theorem from complex analysis. The residue theorem states that for a simply connected domain $D$ in the complex plane and a meromorphic function $f(z)$ within $D$, the integral of $f(z)$ around a closed contour $C$ within $D$ is equal to $2\pi i$ times the sum of the residues of $f(z)$ at its poles within $C$.

In our case, the function $f(z)/(z-z_1)(z-z_2)$ is meromorphic in the ball $B(0,r)$ with simple poles at $z_1$ and $z_2$. We need to integrate this function around the circle $|z|=r$.

First, let's find the residues of $f(z)/(z-z_1)(z-z_2)$ at $z_1$ and $z_2$.

The residue at $z_1$ is given by:
$$\text{Res}(f(z)/(z-z_1)(z-z_2), z_1) = \lim_{z \to z_1} (z-z_1) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_1)}{z_1-z_2}$$

Similarly, the residue at $z_2$ is:
$$\text{Res}(f(z)/(z-z_1)(z-z_2), z_2) = \lim_{z \to z_2} (z-z_2) \frac{f(z)}{(z-z_1)(z-z_2)} = \frac{f(z_2)}{z_2-z_1}$$

Now, we can apply the residue theorem:
$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i \left(\frac{f(z_1)}{z_1-z_2} + \frac{f(z_2)}{z_2-z_1}\right)$$

Simplifying, we get:
$$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz = 2\pi i \left(\frac{f(z_1) - f(z_2)}{z_1-z_2}\right)$$

This is the value of the integral.
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doubao Since f is a bounded entire function, by Liouville's theorem, f is constant. Let f(z) = C (a constant).

Now, consider the integral $\int_{|z|=r} \frac{C}{(z-z_1)(z-z_2)} dz$.

Using the residue theorem, the residues at z = z_1 and z = z_2 are given by:

Residue at z = z_1: $C \lim_{z \to z_1} \frac{1}{z-z_2} = \frac{C}{z_1-z_2}$.

Residue at z = z_2: $C \lim_{z \to z_2} \frac{1}{z-z_1} = \frac{C}{z_2-z_1}$.

The value of the integral is 2πi times the sum of the residues, so it is:

$2\pi i \left(\frac{C}{z_1-z_2} + \frac{C}{z_2-z_1}\right) = 2\pi i C \left(\frac{z_2-z_1 + z_1-z_2}{(z_1-z_2)(z_2-z_1)}\right) = 0$.
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minimax To solve this problem, we can use the residue theorem from complex analysis. The residue theorem states that if \( f(z) \) is a function that is analytic inside and on a simple closed contour \( C \), except for a finite number of singular points \( z_1, z_2, ..., z_n \) inside \( C \), then

\[
\int_C \frac{f(z)}{(z - z_1)(z - z_2)...(z - z_n)} dz = 2\pi i \sum \text{Res}(f, z_k)
\]

where \( \text{Res}(f, z_k) \) is the residue of \( f \) at the point \( z_k \).

In our case, \( f(z) \) is an entire function, which means it is analytic everywhere in the complex plane. Since \( f(z) \) is bounded, by Liouville's theorem, \( f(z) \) must be a constant function. Let's call this constant \( c \).

The integral we are given is

\[
\int_{|z|=r} \frac{f(z)}{(z - z_1)(z - z_2)} dz
\]

Since \( f(z) \) is constant, we can take \( c \) out of the integral:

\[
\int_{|z|=r} \frac{c}{(z - z_1)(z - z_2)} dz = c \int_{|z|=r} \frac{1}{(z - z_1)(z - z_2)} dz
\]

Now, we can apply the residue theorem to this integral. The singular points inside the contour \( |z|=r \) are \( z_1 \) and \( z_2 \). The residues of the function \( \frac{1}{(z - z_1)(z - z_2)} \) at \( z_1 \) and \( z_2 \) are

\[
\text{Res}\left(\frac{1}{(z - z_1)(z - z_2)}, z_1\right) = \frac{1}{z_2 - z_1}
\]

\[
\text{Res}\left(\frac{1}{(z - z_1)(z - z_2)}, z_2\right) = \frac{1}{z_1 - z_2}
\]

Applying the residue theorem, we get

\[
c \int_{|z|=r} \frac{1}{(z - z_1)(z - z_2)} dz = c \cdot 2\pi i \left( \frac{1}{z_2 - z_1} + \frac{1}{z_1 - z_2} \right)
\]

Notice that the second term in the parentheses is the negative of the first term, so they cancel each other out:

\[
c \cdot 2\pi i \left( \frac{1}{z_2 - z_1} + \frac{1}{z_1 - z_2} \right) = c \cdot 2\pi i \left( \frac{1}{z_2 - z_1} - \frac{1}{z_2 - z_1} \right) = 0
\]

Therefore, the value of the integral is

\[
\int_{|z|=r} \frac{f(z)}{(z - z_1)(z - z_2)} dz = 0
\]

This result is independent of the value of \( c \) since \( f(z) \) is constant and the integral of a constant times a function with equal and opposite residues over a closed contour is zero.
0.0
kimi To solve this problem, we can use the properties of analytic functions and Cauchy's integral formula. Since f is a bounded entire function, it is also analytic everywhere in the complex plane, including the boundary of the ball \( B(0, r) \).

Cauchy's integral formula states that for a function \( f \) that is analytic inside and on a simple closed contour \( C \), and for any point \( z_0 \) inside \( C \), the following holds:

\[
f(z_0) = \frac{1}{2\pi i} \int_C \frac{f(z)}{z - z_0} dz
\]

Now, let's consider the integral given in the problem:

\[
\int_{|z|=r} \frac{f(z)}{(z - z_1)(z - z_2)} dz
\]

Since \( z_1 \) and \( z_2 \) are points inside the ball \( B(0, r) \), the function \( f(z)/(z - z_1) \) is analytic inside and on the boundary of the ball \( B(0, r) \). However, \( f(z)/(z - z_2) \) has a simple pole at \( z = z_2 \) inside the ball, which means we cannot directly apply Cauchy's integral formula to this function.

Instead, we can use the fact that the integral of an analytic function around a closed contour is zero:

\[
\int_{|z|=r} \frac{f(z)}{(z - z_1)(z - z_2)} dz = 0
\]

This is because the function \( f(z)/(z - z_1) \) is analytic inside the contour \( |z| = r \), and the function \( 1/(z - z_2) \) has a simple pole at \( z = z_2 \), which is inside the contour. The integral of an analytic function over a closed contour is zero, and the integral of a function with a simple pole inside the contour is equal to \( 2\pi i \) times the residue of the function at the pole.

However, since \( f(z) \) is entire and bounded, the function \( f(z)/(z - z_2) \) is also bounded and analytic everywhere except at \( z = z_2 \). Therefore, the integral of \( f(z)/(z - z_1)(z - z_2) \) over the contour \( |z| = r \) is zero because the function has no singularities on the contour.

So, the value of the integral is:

\[
\int_{|z|=r} \frac{f(z)}{(z - z_1)(z - z_2)} dz = 0
\]
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wenxinyiyan 首先,由于$f$是有界整函数,根据刘维尔定理,我们可以推断出$f$是常数。设$f(z)=c$,其中$c$是常数。

接下来,我们考虑积分$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz$。

由于$f(z)=c$,我们可以将积分重写为$\int_{|z|=r} \frac{c}{(z-z_1)(z-z_2)} dz$。

现在,我们可以使用柯西积分公式来计算这个积分。根据柯西积分公式,我们有

$\int_{|z|=r} \frac{c}{(z-z_1)(z-z_2)} dz = 2\pi i c \left( \frac{1}{z_1-z_2} \right)$,其中$z_1$和$z_2$都在圆$|z|=r$内。

因此,积分$\int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} dz$的值为$2\pi i c \left( \frac{1}{z_1-z_2} \right)$。
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zhipu To solve the problem of finding the value of the integral

\[ \int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} \, dz, \]

where \( f \) is a bounded entire function and \( z_1, z_2 \) are points within the ball \( B(0,r) \), we can use the Cauchy Integral Formula and the properties of entire functions.

### Step-by-Step Solution:

1. **Bounded Entire Function**:
Since \( f \) is an entire function (holomorphic everywhere in the complex plane) and bounded, by Liouville's Theorem, \( f \) must be a constant function. Let \( f(z) = C \) for some constant \( C \).

2. **Simplify the Integral**:
Given that \( f(z) = C \), the integral simplifies to

\[ \int_{|z|=r} \frac{C}{(z-z_1)(z-z_2)} \, dz = C \int_{|z|=r} \frac{1}{(z-z_1)(z-z_2)} \, dz. \]

3. **Cauchy Integral Formula**:
The Cauchy Integral Formula states that for a function \( g(z) \) holomorphic inside and on a simple closed contour \( \gamma \) enclosing the point \( a \),

\[ \int_{\gamma} \frac{g(z)}{z-a} \, dz = 2\pi i g(a). \]

However, in our case, the integrand has two poles \( z_1 \) and \( z_2 \) inside the contour \( |z|=r \).

4. **Residue Theorem**:
To evaluate the integral, we use the Residue Theorem. The integrand \( \frac{1}{(z-z_1)(z-z_2)} \) has simple poles at \( z_1 \) and \( z_2 \). The residue of \( \frac{1}{(z-z_1)(z-z_2)} \) at \( z = z_1 \) is

\[ \text{Res}\left( \frac{1}{(z-z_1)(z-z_2)}, z = z_1 \right) = \frac{1}{z_1 - z_2}, \]

and the residue at \( z = z_2 \) is

\[ \text{Res}\left( \frac{1}{(z-z_1)(z-z_2)}, z = z_2 \right) = \frac{1}{z_2 - z_1}. \]

5. **Apply the Residue Theorem**:
The Residue Theorem states that for a function with poles inside a contour \( \gamma \),

\[ \int_{\gamma} \frac{1}{(z-z_1)(z-z_2)} \, dz = 2\pi i \left( \text{Res}(z=z_1) + \text{Res}(z=z_2) \right). \]

Substituting the residues, we get

\[ \int_{|z|=r} \frac{1}{(z-z_1)(z-z_2)} \, dz = 2\pi i \left( \frac{1}{z_1 - z_2} + \frac{1}{z_2 - z_1} \right). \]

Since \( \frac{1}{z_1 - z_2} + \frac{1}{z_2 - z_1} = 0 \),

\[ \int_{|z|=r} \frac{1}{(z-z_1)(z-z_2)} \, dz = 0. \]

6. **Final Result**:
Therefore, the value of the integral is

\[ \int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} \, dz = C \cdot 0 = 0. \]

### Conclusion:
The value of the integral \( \int_{|z|=r} \frac{f(z)}{(z-z_1)(z-z_2)} \, dz \) is \( \boxed{0} \).
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gpto1 To solve the problem, we are asked to evaluate the integral
\[
I = \int_{|z|=r} \frac{f(z)}{(z - z_1)(z - z_2)} \, dz
\]
where \( f \) is a bounded entire function, and \( z_1, z_2 \) are two points inside the circle \( |z|=r \).

**Step 1: Recognize that \( f \) is constant**

Since \( f \) is an entire (analytic everywhere in the complex plane) and bounded function, Liouville's Theorem tells us that \( f \) must be constant. That is,
\[
f(z) = c
\]
for some constant \( c \).

**Step 2: Simplify the integral**

Substituting \( f(z) = c \) into the integral, we have
\[
I = c \int_{|z|=r} \frac{1}{(z - z_1)(z - z_2)} \, dz
\]

**Step 3: Compute the integral using the Residue Theorem**

The integrand has simple poles at \( z = z_1 \) and \( z = z_2 \), both inside the circle \( |z|=r \). By the Residue Theorem,
\[
I = 2\pi i \times \left( \operatorname{Res}_{z=z_1} \frac{1}{(z - z_1)(z - z_2)} + \operatorname{Res}_{z=z_2} \frac{1}{(z - z_1)(z - z_2)} \right)
\]

**Computing the residues:**

- At \( z = z_1 \):
\[
\operatorname{Res}_{z=z_1} \frac{1}{(z - z_1)(z - z_2)} = \lim_{z \to z_1} (z - z_1) \frac{1}{(z - z_1)(z - z_2)} = \frac{1}{z_1 - z_2}
\]

- At \( z = z_2 \):
\[
\operatorname{Res}_{z=z_2} \frac{1}{(z - z_1)(z - z_2)} = \lim_{z \to z_2} (z - z_2) \frac{1}{(z - z_1)(z - z_2)} = \frac{1}{z_2 - z_1} = -\frac{1}{z_1 - z_2}
\]

**Step 4: Sum of the residues**

Adding the residues:
\[
\operatorname{Res}_{z=z_1} + \operatorname{Res}_{z=z_2} = \frac{1}{z_1 - z_2} - \frac{1}{z_1 - z_2} = 0
\]

**Step 5: Evaluate the integral**

Since the sum of the residues is zero:
\[
I = 2\pi i \times 0 = 0
\]

Thus, the value of the original integral is zero.

**Answer:**
0
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