问题


There is a single choice question about high school mathematics. Answer the question by replying A, B, C or D.
Question: If we express $3x^2 + x - 4$ in the form $a(x - h)^2 + k$, then what is $k$?
A. -\frac{7}{12}
B. -7
C. 49
D. -\frac{49}{12}
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

D. -\frac{49}{12}
D
deepseekr1

To convert \(3x^2 + x - 4\) into vertex form \(a(x - h)^2 + k\), follow these steps:

1. **Factor out the coefficient of \(x^2\) from the first two terms**:
\(3x^2 + x - 4 = 3\left(x^2 + \frac{1}{3}x\right) - 4\).

2. **Complete the square inside the parentheses**:
- The coefficient of \(x\) is \(\frac{1}{3}\). Half of this is \(\frac{1}{6}\), and squaring it gives \(\left(\frac{1}{6}\right)^2 = \frac{1}{36}\).
- Add and subtract \(\frac{1}{36}\) inside the parentheses:
\[
3\left[\left(x^2 + \frac{1}{3}x + \frac{1}{36}\right) - \frac{1}{36}\right] - 4.
\]

3. **Simplify the expression**:
- The squared term becomes \(\left(x + \frac{1}{6}\right)^2\).
- Distribute the factor of 3 and combine constants:
\[
3\left(x + \frac{1}{6}\right)^2 - 3 \cdot \frac{1}{36} - 4 = 3\left(x + \frac{1}{6}\right)^2 - \frac{1}{12} - 4.
\]
- Convert \(-4\) to twelfths: \(-4 = -\frac{48}{12}\).
- Combine constants: \(-\frac{1}{12} - \frac{48}{12} = -\frac{49}{12}\).

Thus, the vertex form is \(3\left(x + \frac{1}{6}\right)^2 - \frac{49}{12}\), and \(k = -\frac{49}{12}\).

**Answer: D**
D
gpto1 To rewrite the quadratic expression \( 3x^2 + x - 4 \) in the form \( a(x - h)^2 + k \), we can complete the square:

1. **Factor out the coefficient of \( x^2 \) from the first two terms:**

\[
3x^2 + x - 4 = 3\left( x^2 + \frac{1}{3}x \right) - 4
\]

2. **Complete the square inside the parentheses:**

- Take half of the coefficient of \( x \): \( \frac{1}{2} \times \frac{1}{3} = \frac{1}{6} \).
- Square it: \( \left( \frac{1}{6} \right)^2 = \frac{1}{36} \).
- Add and subtract this inside the parentheses:

\[
3\left( \left( x + \frac{1}{6} \right)^2 - \frac{1}{36} \right) - 4
\]

3. **Simplify the expression:**

- Distribute the 3:

\[
3\left( x + \frac{1}{6} \right)^2 - \frac{3}{36} - 4
\]

- Simplify \( \frac{3}{36} \):

\[
3\left( x + \frac{1}{6} \right)^2 - \frac{1}{12} - 4
\]

- Combine constants:

\[
-\frac{1}{12} - 4 = -\frac{1}{12} - \frac{48}{12} = -\frac{49}{12}
\]

- Final form:

\[
3\left( x + \frac{1}{6} \right)^2 - \frac{49}{12}
\]

So, the value of \( k \) is \( -\dfrac{49}{12} \).

**Answer: D. \(-\dfrac{49}{12}\)**
D
GPT-4o To convert the quadratic expression \(3x^2 + x - 4\) into the form \(a(x - h)^2 + k\), we need to complete the square.

First, we start with the given quadratic equation:
\[3x^2 + x - 4\]

We factor out the coefficient of \(x^2\) from the first two terms:
\[3(x^2 + \frac{1}{3}x) - 4\]

Next, we complete the square inside the parentheses. To do this, we take the coefficient of \(x\), divide by 2, and square it:
\[\left(\frac{1}{3} \cdot \frac{1}{2}\right)^2 = \left(\frac{1}{6}\right)^2 = \frac{1}{36}\]

We add and subtract this value inside the parentheses:
\[3\left(x^2 + \frac{1}{3}x + \frac{1}{36} - \frac{1}{36}\right) - 4\]
\[= 3\left(\left(x + \frac{1}{6}\right)^2 - \frac{1}{36}\right) - 4\]

Then, we distribute the 3:
\[= 3\left(x + \frac{1}{6}\right)^2 - 3 \cdot \frac{1}{36} - 4\]
\[= 3\left(x + \frac{1}{6}\right)^2 - \frac{3}{36} - 4\]
\[= 3\left(x + \frac{1}{6}\right)^2 - \frac{1}{12} - 4\]

Combine the constants:
\[= 3\left(x + \frac{1}{6}\right)^2 - \left(\frac{1}{12} + 4\right)\]
\[= 3\left(x + \frac{1}{6}\right)^2 - \left(\frac{1}{12} + \frac{48}{12}\right)\]
\[= 3\left(x + \frac{1}{6}\right)^2 - \frac{49}{12}\]

So, in the form \(a(x - h)^2 + k\), we have \(a = 3\), \(h = -\frac{1}{6}\), and \(k = -\frac{49}{12}\).

Therefore, the value of \(k\) is:
\[D. -\frac{49}{12}\]

Answer: D
D
llama3.1-70B-Instruct

## Step 1: To express the given quadratic equation $3x^2 + x - 4$ in the form $a(x - h)^2 + k$, we need to complete the square.
## Step 2: The general form of completing the square for a quadratic $ax^2 + bx + c$ is $a(x - h)^2 + k$, where $h = -\frac{b}{2a}$ and $k = c - \frac{b^2}{4a}$.
## Step 3: From the given equation $3x^2 + x - 4$, we can identify $a = 3$, $b = 1$, and $c = -4$.
## Step 4: Now, we can calculate the value of $k$ using the formula $k = c - \frac{b^2}{4a}$.
## Step 5: Plugging in the values, we get $k = -4 - \frac{1^2}{4 \cdot 3} = -4 - \frac{1}{12} = -\frac{48}{12} - \frac{1}{12} = -\frac{49}{12}$.

The final answer is: $\boxed{D}$
D
llama3.1-405B-Instruct

D.
D
DeepSeek-Coder-V2 D D
Qwen2-72B-Instruct D. -\frac{49}{12} D
baichuan4 To express $3x^2 + x - 4$ in the form $a(x - h)^2 + k$, we need to complete the square.

First, divide the coefficient of $x^2$, which is 3, to get:
$$3x^2 + x - 4 = 3(x^2 + \frac{1}{3}x) - 4$$

To complete the square, we add the square of half the coefficient of $x$ (inside the parentheses), and subtract the same amount outside the parentheses multiplied by the coefficient of $x^2$ (which is 3 in this case):
$$3(x^2 + \frac{1}{3}x + (\frac{1}{6})^2) - 4 - 3(\frac{1}{6})^2$$

Calculate the terms:
$$3(x^2 + \frac{1}{3}x + \frac{1}{36}) - 4 - \frac{1}{12}$$

Expand and simplify:
$$3x^2 + x + \frac{1}{12} - 4 - \frac{1}{12}$$

$$3x^2 + x - \frac{49}{12}$$

Now, we can see that $k = -\frac{49}{12}$.

Answer: D. $-\frac{49}{12}$
D
doubao D. -\frac{49}{12}

To express $3x^2 + x - 4$ in the form $a(x - h)^2 + k$, we complete the square.

$3x^2 + x - 4 = 3(x^2 + \frac{1}{3}x) - 4 = 3(x^2 + \frac{1}{3}x + \frac{1}{36} - \frac{1}{36}) - 4 = 3[(x + \frac{1}{6})^2 - \frac{1}{36}] - 4 = 3(x + \frac{1}{6})^2 - \frac{1}{12} - 4 = 3(x + \frac{1}{6})^2 - \frac{49}{12}$. So $k = -\frac{49}{12}$.
D
minimax To express $3x^2 + x - 4$ in the form $a(x - h)^2 + k$, we need to complete the square. Here's how you do it:

First, factor out the coefficient of $x^2$ from the first two terms:

$3(x^2 + \frac{1}{3}x) - 4$

Now, to complete the square inside the parentheses, we need to add and subtract the square of half the coefficient of $x$ inside the parentheses. The coefficient of $x$ is $\frac{1}{3}$, so half of that is $\frac{1}{6}$, and squaring that gives us $\left(\frac{1}{6}\right)^2 = \frac{1}{36}$.

Add and subtract $\frac{1}{36}$ inside the parentheses:

$3\left(x^2 + \frac{1}{3}x + \frac{1}{36} - \frac{1}{36}\right) - 4$

Now, rewrite the expression grouping the perfect square trinomial and the constant term:

$3\left(\left(x + \frac{1}{6}\right)^2 - \frac{1}{36}\right) - 4$

Distribute the 3:

$3\left(x + \frac{1}{6}\right)^2 - 3 \cdot \frac{1}{36} - 4$

$3\left(x + \frac{1}{6}\right)^2 - \frac{1}{12} - 4$

Now, combine the constants:

$3\left(x + \frac{1}{6}\right)^2 - \frac{49}{12}$

So, in the form $a(x - h)^2 + k$, $k$ is $-\frac{49}{12}$.

The correct answer is:

D. -\frac{49}{12}
D
kimi To express the quadratic function \(3x^2 + x - 4\) in the form \(a(x - h)^2 + k\), we need to complete the square. Here's how you do it:

1. Factor out the coefficient of \(x^2\) from the first two terms:
\[
3x^2 + x - 4 = 3(x^2 + \frac{1}{3}x) - 4
\]

2. To complete the square inside the parentheses, take half of the coefficient of \(x\), which is \(\frac{1}{6}\), square it to get \(\frac{1}{36}\), and add and subtract this value inside the parentheses:
\[
3(x^2 + \frac{1}{3}x + \frac{1}{36} - \frac{1}{36}) - 4
\]

3. Rewrite the expression by combining the perfect square trinomial and the constants:
\[
3((x + \frac{1}{6})^2 - \frac{1}{36}) - 4
\]

4. Distribute the 3 and simplify:
\[
3(x + \frac{1}{6})^2 - \frac{1}{12} - 4
\]

5. Combine the constants:
\[
3(x + \frac{1}{6})^2 - \frac{49}{12}
\]

So, the expression \(3x^2 + x - 4\) in the form \(a(x - h)^2 + k\) is \(3(x + \frac{1}{6})^2 - \frac{49}{12}\), and the value of \(k\) is \(-\frac{49}{12}\).

Answer: D. -\frac{49}{12}
D
wenxinyiyan D D
zhipu To express the quadratic \( 3x^2 + x - 4 \) in the form \( a(x - h)^2 + k \), we need to complete the square.

First, factor out the coefficient of \( x^2 \) from the first two terms:
\[ 3x^2 + x - 4 = 3(x^2 + \frac{1}{3}x) - 4 \]

Next, complete the square inside the parentheses. Take half of the coefficient of \( x \), square it, and add and subtract this value inside the parentheses:
\[ 3 \left( x^2 + \frac{1}{3}x + \left( \frac{1}{6} \right)^2 - \left( \frac{1}{6} \right)^2 \right) - 4 \]
\[ = 3 \left( \left( x + \frac{1}{6} \right)^2 - \frac{1}{36} \right) - 4 \]

Now, distribute the 3 and simplify:
\[ = 3 \left( x + \frac{1}{6} \right)^2 - 3 \cdot \frac{1}{36} - 4 \]
\[ = 3 \left( x + \frac{1}{6} \right)^2 - \frac{1}{12} - 4 \]
\[ = 3 \left( x + \frac{1}{6} \right)^2 - \frac{1}{12} - \frac{48}{12} \]
\[ = 3 \left( x + \frac{1}{6} \right)^2 - \frac{49}{12} \]

From this form, we see that \( k = -\frac{49}{12} \).

Thus, the correct answer is:
D. -\frac{49}{12}
D
gpto1 To rewrite the quadratic expression \( 3x^2 + x - 4 \) in the form \( a(x - h)^2 + k \), we can complete the square:

1. **Factor out the coefficient of \( x^2 \) from the first two terms:**

\[
3x^2 + x - 4 = 3\left( x^2 + \frac{1}{3}x \right) - 4
\]

2. **Complete the square inside the parentheses:**

- Take half of the coefficient of \( x \): \( \frac{1}{2} \times \frac{1}{3} = \frac{1}{6} \).
- Square it: \( \left( \frac{1}{6} \right)^2 = \frac{1}{36} \).
- Add and subtract this inside the parentheses:

\[
3\left( \left( x + \frac{1}{6} \right)^2 - \frac{1}{36} \right) - 4
\]

3. **Simplify the expression:**

- Distribute the 3:

\[
3\left( x + \frac{1}{6} \right)^2 - \frac{3}{36} - 4
\]

- Simplify \( \frac{3}{36} \):

\[
3\left( x + \frac{1}{6} \right)^2 - \frac{1}{12} - 4
\]

- Combine constants:

\[
-\frac{1}{12} - 4 = -\frac{1}{12} - \frac{48}{12} = -\frac{49}{12}
\]

- Final form:

\[
3\left( x + \frac{1}{6} \right)^2 - \frac{49}{12}
\]

So, the value of \( k \) is \( -\dfrac{49}{12} \).

**Answer: D. \(-\dfrac{49}{12}\)**
D
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