问题


There is a single choice question about high school mathematics. Answer the question by replying A, B, C or D.
Question: Find the sum of all integers $k$ such that $\binom{23}{4} + \binom{23}{5} = \binom{24}{k}$.
A. 24
B. 5
C. 3
D. 21
Answer:

答案

模型 模型答案 正确答案
金声玉亮2.0

A
The best answer is A
A
deepseekr1

The problem involves finding the sum of all integers \( k \) such that \( \binom{23}{4} + \binom{23}{5} = \binom{24}{k} \). Using Pascal's identity, \( \binom{n}{r} + \binom{n}{r+1} = \binom{n+1}{r+1} \), substituting \( n = 23 \) and \( r = 4 \), we get:
\[
\binom{23}{4} + \binom{23}{5} = \binom{24}{5}.
\]
Due to the symmetry property of combinations (\( \binom{n}{k} = \binom{n}{n-k} \)), \( \binom{24}{5} = \binom{24}{19} \). Thus, \( k \) can be either 5 or 19. The sum of these values is \( 5 + 19 = 24 \).

**Answer:** A. 24
A
gpto1 To solve this problem, we need to find all integer values of \( k \) such that:

\[
\binom{23}{4} + \binom{23}{5} = \binom{24}{k}
\]

First, let's recognize a key identity in combinatorics:

\[
\binom{n}{k} + \binom{n}{k-1} = \binom{n+1}{k}
\]

Using this identity with \( n = 23 \) and \( k = 5 \):

\[
\binom{23}{5} + \binom{23}{4} = \binom{24}{5}
\]

This simplifies our equation to:

\[
\binom{24}{5} = \binom{24}{k}
\]

This implies that \( k \) must satisfy:

\[
\binom{24}{k} = \binom{24}{5}
\]

Since the binomial coefficient satisfies \( \binom{n}{k} = \binom{n}{n - k} \), the values of \( k \) that satisfy the equation are:

\[
k = 5 \quad \text{or} \quad k = 24 - 5 = 19
\]

Therefore, the sum of all such integers \( k \) is:

\[
5 + 19 = 24
\]

**Answer:** A. 24
A
GPT-4o To find the sum of all integers \( k \) such that \( \binom{23}{4} + \binom{23}{5} = \binom{24}{k} \), we can use the Pascal's identity for binomial coefficients. Pascal's identity states that:

\[ \binom{n}{r} + \binom{n}{r+1} = \binom{n+1}{r+1}. \]

In this case, we have \( n = 23 \) and \( r = 4 \). Applying Pascal's identity, we get:

\[ \binom{23}{4} + \binom{23}{5} = \binom{24}{5}. \]

So, \( \binom{24}{k} = \binom{24}{5} \). This implies that \( k = 5 \).

Since there is only one \( k \) that satisfies the equation, the sum of all such \( k \) is simply \( 5 \).

Therefore, the answer is:

B. 5
A
llama3.1-70B-Instruct

A
Pascal's Identity states that $\binom{n}{r} + \binom{n}{r+1} = \binom{n+1}{r+1}$. Thus, $\binom{23}{4} + \binom{23}{5} = \binom{24}{5}$. Since $\binom{24}{5} = \binom{24}{24-5} = \binom{24}{19}$, the sum of all integers $k$ such that $\binom{23}{4} + \binom{23}{5} = \binom{24}{k}$ is $5+19=24$.
Final Answer: The final answer is 24. I hope it is correct.
A
llama3.1-405B-Instruct

A
The best answer is A.
A
DeepSeek-Coder-V2 A. 24 A
Qwen2-72B-Instruct A. 24

Explanation: The given equation is $\binom{23}{4} + \binom{23}{5} = \binom{24}{k}$. By Pascal's Identity, we know that $\binom{n}{r} + \binom{n}{r+1} = \binom{n+1}{r+1}$. Applying this identity to the given equation, we get $\binom{24}{5} = \binom{24}{k}$. The binomial coefficient $\binom{n}{r}$ is equal to $\binom{n}{n-r}$, so $\binom{24}{5} = \binom{24}{24-5} = \binom{24}{19}$. Therefore, the possible values of $k$ are 5 and 19. The sum of these values is $5 + 19 = 24$.
A
baichuan4 B A
doubao Using the combination formula $C_n^m=\frac{n!}{m!(n-m)!}$, we have:

$\binom{23}{4}+\binom{23}{5}=\frac{23!}{4!(23-4)!}+\frac{23!}{5!(23-5)!}=\frac{23!}{4!19!}+\frac{23!}{5!18!}=\frac{23\times22\times21\times20}{4\times3\times2\times1}+\frac{23\times22\times21\times20\times19}{5\times4\times3\times2\times1}=\frac{23\times22\times21\times20}{24}+\frac{23\times22\times21\times20\times19}{120}=(23\times22\times21\times20)\times(\frac{1}{24}+\frac{19}{120})=(23\times22\times21\times20)\times(\frac{5}{120}+\frac{19}{120})=(23\times22\times21\times20)\times\frac{24}{120}=23\times11\times21\times2=253\times21$.

And $\binom{24}{k}=\frac{24!}{k!(24-k)!}$.

So we need to find $k$ such that $\frac{24!}{k!(24-k)!}=253\times21$.

By checking the options, we find that when $k=5$, $\binom{24}{5}=\frac{24!}{5!(24-5)!}=\frac{24\times23\times22\times21\times20}{5\times4\times3\times2\times1}=253\times21$.

So the answer is B.
A
minimax To solve this problem, we can use Pascal's rule, which states that for any non-negative integers $n$ and $r$:

$$\binom{n}{r} + \binom{n}{r+1} = \binom{n+1}{r+1}$$

Given the equation:

$$\binom{23}{4} + \binom{23}{5} = \binom{24}{k}$$

We can apply Pascal's rule with $n = 23$ and $r = 4$:

$$\binom{23}{4} + \binom{23}{5} = \binom{24}{5}$$

Therefore, we have:

$$\binom{24}{k} = \binom{24}{5}$$

This implies that $k = 5$ because the binomial coefficient $\binom{n}{r}$ is equal to $\binom{n}{n-r}$, and there is only one value of $k$ that satisfies the equation.

The answer is:

B. 5
A
kimi To solve this problem, we can use the identity for binomial coefficients that states:

\[
\binom{n}{r} + \binom{n}{r+1} = \binom{n+1}{r+1}
\]

Given the equation:

\[
\binom{23}{4} + \binom{23}{5} = \binom{24}{k}
\]

We can apply the identity with \( n = 23 \) and \( r = 4 \):

\[
\binom{23}{4} + \binom{23}{5} = \binom{24}{5}
\]

This means that \( k = 5 \). Now we need to find the sum of all integers \( k \) that satisfy the equation. Since the binomial coefficient is symmetric, we also have:

\[
\binom{24}{5} = \binom{24}{24-5} = \binom{24}{19}
\]

So, the values of \( k \) that satisfy the equation are \( k = 5 \) and \( k = 19 \). Adding these together:

\[
k + (24 - k) = 5 + 19 = 24
\]

Therefore, the sum of all integers \( k \) is 24.

Answer: A. 24
A
wenxinyiyan B

Explanation:
Using Pascal's Identity, which states that $\binom{n}{k} = \binom{n-1}{k} + \binom{n-1}{k-1}$, we can rewrite the given equation as follows:
$\binom{23}{4} + \binom{23}{5} = \binom{24}{5}$
This is because when $n = 24$ and $k = 5$, Pascal's Identity gives:
$\binom{24}{5} = \binom{23}{5} + \binom{23}{4}$
Since the equation $\binom{23}{4} + \binom{23}{5} = \binom{24}{k}$ holds true for $k = 5$, the sum of all integers $k$ that satisfy the equation is simply 5.
A
zhipu To solve the problem, we will use the properties of binomial coefficients.

We start with the given equation:
\[
\binom{23}{4} + \binom{23}{5} = \binom{24}{k}
\]

Using the property of binomial coefficients, specifically Pascal's identity, we know:
\[
\binom{n}{r} + \binom{n}{r+1} = \binom{n+1}{r+1}
\]

In our case, \( n = 23 \) and \( r = 4 \). Applying Pascal's identity:
\[
\binom{23}{4} + \binom{23}{5} = \binom{24}{5}
\]

This means:
\[
\binom{24}{k} = \binom{24}{5}
\]

Since binomial coefficients are symmetric, we have:
\[
\binom{24}{k} = \binom{24}{24-k}
\]

Therefore, \( k \) can be either 5 or \( 24 - 5 = 19 \).

The sum of all integers \( k \) that satisfy the equation is:
\[
5 + 19 = 24
\]

Thus, the correct answer is:
\[
\boxed{24}
\]
A
gpto1 To solve this problem, we need to find all integer values of \( k \) such that:

\[
\binom{23}{4} + \binom{23}{5} = \binom{24}{k}
\]

First, let's recognize a key identity in combinatorics:

\[
\binom{n}{k} + \binom{n}{k-1} = \binom{n+1}{k}
\]

Using this identity with \( n = 23 \) and \( k = 5 \):

\[
\binom{23}{5} + \binom{23}{4} = \binom{24}{5}
\]

This simplifies our equation to:

\[
\binom{24}{5} = \binom{24}{k}
\]

This implies that \( k \) must satisfy:

\[
\binom{24}{k} = \binom{24}{5}
\]

Since the binomial coefficient satisfies \( \binom{n}{k} = \binom{n}{n - k} \), the values of \( k \) that satisfy the equation are:

\[
k = 5 \quad \text{or} \quad k = 24 - 5 = 19
\]

Therefore, the sum of all such integers \( k \) is:

\[
5 + 19 = 24
\]

**Answer:** A. 24
A
deepseekv3 To solve the problem, we start by simplifying the given equation:

\[
\binom{23}{4} + \binom{23}{5} = \binom{24}{k}
\]

Using the **Pascal's Identity**, we know that:

\[
\binom{n}{k} + \binom{n}{k+1} = \binom{n+1}{k+1}
\]

Applying this to the left-hand side of the equation with \( n = 23 \) and \( k = 4 \):

\[
\binom{23}{4} + \binom{23}{5} = \binom{24}{5}
\]

Thus, the equation becomes:

\[
\binom{24}{5} = \binom{24}{k}
\]

Since binomial coefficients are symmetric, \(\binom{24}{k} = \binom{24}{24 - k}\). Therefore, the possible values of \( k \) are:

\[
k = 5 \quad \text{or} \quad k = 24 - 5 = 19
\]

The sum of all possible integers \( k \) is:

\[
5 + 19 = 24
\]

**Final Answer:**

\boxed{A}
A