问题


以下是关于高中数学的单项选择题,请直接给出正确答案的选项。
题目:等差数列{a_N}中,若$a_2+a_3=4$,$a_4+a_5=6$,则$a_9+a_{10}=$
A. 11
B. 12
C. 10
D. 9
答案是:

答案

模型 模型答案 正确答案
金声玉亮2.0 设等差数列的首项为$a_1$,公差为$d$。

由题意知:
\[a_2 + a_3 = 4\]
\[a_4 + a_5 = 6\]

根据等差数列的通项公式$a_n = a_1 + (n-1)d$,可以将上述两式写为:
\[(a_1 + d) + (a_1 + 2d) = 4\]
\[(a_1 + 3d) + (a_1 + 4d) = 6\]

化简得:
\[2a_1 + 3d = 4\]
\[2a_1 + 7d = 6\]

两式相减得:
\[4d = 2\]
\[d = \frac{1}{2}\]

将$d = \frac{1}{2}$代入$2a_1 + 3d = 4$中,得:
\[2a_1 + \frac{3}{2} = 4\]
\[2a_1 = \frac{5}{2}\]
\[a_1 = \frac{5}{4}\]

要求$a_9 + a_{10}$,根据通项公式:
\[a_9 = a_1 + 8d = \frac{5}{4} + 8 \times \frac{1}{2} = \frac{5}{4} + 4 = \frac{21}{4}\]
\[a_{10} = a_1 + 9d = \frac{5}{4} + 9 \times \frac{1}{2} = \frac{5}{4} + \frac{9}{2} = \frac{5}{4} + \frac{18}{4} = \frac{23}{4}\]

所以:
\[a_9 + a_{10} = \frac{21}{4} + \frac{23}{4} = \frac{44}{4} = 11\]

答案是:A. 11
A
deepseekr1

等差数列{aₙ}中,已知a₂ + a₃ = 4,a₄ + a₅ = 6,求a₉ + a₁₀的值。

首先,根据等差数列的通项公式aₙ = a₁ + (n-1)d,其中a₁是首项,d是公差。

根据题目给出的条件:
1. a₂ + a₃ = (a₁ + d) + (a₁ + 2d) = 2a₁ + 3d = 4
2. a₄ + a₅ = (a₁ + 3d) + (a₁ + 4d) = 2a₁ + 7d = 6

解方程组:
1. 2a₁ + 3d = 4
2. 2a₁ + 7d = 6

用第二个方程减去第一个方程,得到:
\[ (2a₁ + 7d) - (2a₁ + 3d) = 6 - 4 \]
\[ 4d = 2 \]
\[ d = \frac{1}{2} \]

将d = 1/2代入第一个方程:
\[ 2a₁ + 3 \times \frac{1}{2} = 4 \]
\[ 2a₁ + \frac{3}{2} = 4 \]
\[ 2a₁ = \frac{5}{2} \]
\[ a₁ = \frac{5}{4} \]

接下来计算a₉和a₁₀的和:
\[ a₉ = a₁ + 8d = \frac{5}{4} + 8 \times \frac{1}{2} = \frac{5}{4} + 4 = \frac{21}{4} \]
\[ a₁₀ = a₁ + 9d = \frac{5}{4} + 9 \times \frac{1}{2} = \frac{5}{4} + \frac{18}{4} = \frac{23}{4} \]

因此,a₉ + a₁₀的和为:
\[ \frac{21}{4} + \frac{23}{4} = \frac{44}{4} = 11 \]

最终答案是选项A。

\boxed{A}
A
gpto1 答案是:A A
GPT-4o 答案是: D. 9 A
llama3.1-70B-Instruct

B
A
llama3.1-405B-Instruct

C
A
DeepSeek-Coder-V2 答案是: B. 12 A
Qwen2-72B-Instruct 答案是: A. 11

解析如下:
设等差数列的首项为$a_1$,公差为$d$。

由题意得:
\[a_2 + a_3 = 4\]

\[(a_1 + d) + (a_1 + 2d) = 4\]
\[2a_1 + 3d = 4\]


\[a_4 + a_5 = 6\]

\[(a_1 + 3d) + (a_1 + 4d) = 6\]
\[2a_1 + 7d = 6\]

将上述两个等式联立,解得:
\[4d = 2\]
\[d = 0.5\]

再将$d = 0.5$代入$2a_1 + 3d = 4$中,解得:
\[2a_1 + 1.5 = 4\]
\[2a_1 = 2.5\]
\[a_1 = 1.25\]

求$a_9 + a_{10}$:
\[a_9 + a_{10} = (a_1 + 8d) + (a_1 + 9d)\]
\[= 2a_1 + 17d\]
\[= 2*1.25 + 17*0.5\]
\[= 2.5 + 8.5\]
\[= 11\]

因此,$a_9 + a_{10} = 11$,选项A正确。
A
baichuan4 B. 12 A
doubao 设等差数列$\{a_n\}$的公差为$d$。

则$(a_4+a_5)-(a_2+a_3)=(a_4-a_2)+(a_5-a_3)=2d+2d=4d=6-4=2$,所以$d=\frac{1}{2}$。

$a_9+a_{10}=(a_2+7d)+(a_3+7d)=(a_2+a_3)+14d=4+14\times\frac{1}{2}=4+7=11$。

所以正确答案是 A 选项。
A
minimax 设等差数列的首项为$a_1$,公差为$d$,则数列的通项公式为$a_n = a_1 + (n-1)d$。

根据题目给出的条件,我们有:
$$a_2 + a_3 = (a_1 + d) + (a_1 + 2d) = 4$$
$$a_4 + a_5 = (a_1 + 3d) + (a_1 + 4d) = 6$$

将这两个等式简化,我们得到:
$$2a_1 + 3d = 4 \quad \text{(1)}$$
$$2a_1 + 7d = 6 \quad \text{(2)}$$

从等式(2)中减去等式(1),我们得到:
$$4d = 2$$
$$d = \frac{1}{2}$$

将$d$的值代入等式(1)中,我们得到:
$$2a_1 + 3 \cdot \frac{1}{2} = 4$$
$$2a_1 + \frac{3}{2} = 4$$
$$2a_1 = 4 - \frac{3}{2}$$
$$2a_1 = \frac{8}{2} - \frac{3}{2}$$
$$2a_1 = \frac{5}{2}$$
$$a_1 = \frac{5}{4}$$

现在我们要求$a_9 + a_{10}$,根据通项公式,我们有:
$$a_9 = a_1 + 8d = \frac{5}{4} + 8 \cdot \frac{1}{2} = \frac{5}{4} + 4 = \frac{5}{4} + \frac{16}{4} = \frac{21}{4}$$
$$a_{10} = a_1 + 9d = \frac{5}{4} + 9 \cdot \frac{1}{2} = \frac{5}{4} + \frac{9}{2} = \frac{5}{4} + \frac{18}{4} = \frac{23}{4}$$

因此:
$$a_9 + a_{10} = \frac{21}{4} + \frac{23}{4} = \frac{44}{4} = 11$$

所以正确答案是:
A. 11
A
kimi C. 10 A
wenxinyiyan A. 11。 A
zhipu 首先,我们设等差数列的首项为 \(a\),公差为 \(d\)。

根据等差数列的定义,我们有:
\[ a_2 = a + d \]
\[ a_3 = a + 2d \]
\[ a_4 = a + 3d \]
\[ a_5 = a + 4d \]

题目给出 \(a_2 + a_3 = 4\),即:
\[ (a + d) + (a + 2d) = 4 \]
\[ 2a + 3d = 4 \quad \text{(1)} \]

题目还给出 \(a_4 + a_5 = 6\),即:
\[ (a + 3d) + (a + 4d) = 6 \]
\[ 2a + 7d = 6 \quad \text{(2)} \]

现在我们有两个方程:
\[ 2a + 3d = 4 \quad \text{(1)} \]
\[ 2a + 7d = 6 \quad \text{(2)} \]

我们用方程 (2) 减去方程 (1):
\[ (2a + 7d) - (2a + 3d) = 6 - 4 \]
\[ 4d = 2 \]
\[ d = \frac{1}{2} \]

将 \(d = \frac{1}{2}\) 代入方程 (1):
\[ 2a + 3 \left( \frac{1}{2} \right) = 4 \]
\[ 2a + \frac{3}{2} = 4 \]
\[ 2a = 4 - \frac{3}{2} \]
\[ 2a = \frac{8}{2} - \frac{3}{2} \]
\[ 2a = \frac{5}{2} \]
\[ a = \frac{5}{4} \]

现在我们需要求 \(a_9 + a_{10}\):
\[ a_9 = a + 8d \]
\[ a_{10} = a + 9d \]

所以:
\[ a_9 + a_{10} = (a + 8d) + (a + 9d) \]
\[ = 2a + 17d \]

将 \(a = \frac{5}{4}\) 和 \(d = \frac{1}{2}\) 代入:
\[ 2a + 17d = 2 \left( \frac{5}{4} \right) + 17 \left( \frac{1}{2} \right) \]
\[ = \frac{10}{4} + \frac{17}{2} \]
\[ = \frac{10}{4} + \frac{34}{4} \]
\[ = \frac{44}{4} \]
\[ = 11 \]

所以,\(a_9 + a_{10} = 11\)。

正确答案是 A. 11。
A
gpto1 答案是:A A
deepseekv3 B A