《2025年暑假乐园辽宁师范大学出版社七年级理综人教版》

1. 下列不是二元一次方程组的是 (C)
A. $\left\{\begin{array}{l} 4x+3y=6,\\ 2x+y=4\end{array}\right. $
B. $\left\{\begin{array}{l} x+y=4,\\ x-y=4\end{array}\right. $
C. $\left\{\begin{array}{l} \frac {1}{x}+y=4,\\ x-y=1\end{array}\right. $
D. $\left\{\begin{array}{l} 3x+5y=25,\\ x+10y=25\end{array}\right. $

答案： C

2. 已知$\left\{\begin{array}{l} x=1,\\ y=2\end{array}\right. $是方程$2mx - y = 10$的解,则$m$的值为 (C)
A. 2
B. 4
C. 6
D. 10

答案： C

3. 用加减消元法解二元一次方程组$\left\{ \begin{array} { l } { 2 x - 3 y = 7 \textcircled { 1 } } \\ { 5 x - 3 y = - 2 \textcircled { 2 } } \end{array} \right. $ 由①-②得到的方程为 (B)
A. $3x = 5$
B. $- 3x = 9$
C. $- 3x - 6y = 9$
D. $3x - 6y = 5$

答案： B

4. 如图,点$O$在直线$AB$上,$OC$为射线,$∠1$比$∠2$的$3$倍少$10^{\circ}$,设$∠1,∠2$的度数分别为$x^{\circ},y^{\circ}$,那么下列求这两个角的度数所列方程组正确的是 (B)

A. $\left\{\begin{array}{l} x + y = 180,\\ x = y - 10\end{array}\right. $
B. $\left\{\begin{array}{l} x + y = 180,\\ x = 3y - 10\end{array}\right. $
C. $\left\{\begin{array}{l} x + y = 180,\\ x = y + 10\end{array}\right. $
D. $\left\{\begin{array}{l} 3y = 180,\\ x = 3y - 10\end{array}\right. $

答案： B

5. 一个两位数的十位数字与个位数字的和是$7$. 如果把这个两位数加上$45$,那么恰好成为这个两位数个位数字与十位数字对调后组成的两位数,则这个两位数是 (D)
A. 36
B. 25
C. 61
D. 16

答案： D

6. 两位同学解方程组时,甲同学由$\left\{\begin{array}{l} ax + by = 2x,\\ cx - 7y = 8\end{array}\right. $正确地解得$\left\{\begin{array}{l} x = 3,\\ y = - 2,\end{array}\right. $乙同学因把$c$写错了而解得$\left\{\begin{array}{l} x = - 2,\\ y = 2,\end{array}\right. $那么$a,b,c$正确的值应为 (A)
A. $a = 2,b = 0,c = - 2$
B. $a = 2,b = 0,c = - 1$
C. $a = - 2,b = 0,c = 0$
D. $a = - 2,b = 0,c = 2$

答案： A