《2025年轻松总复习暑假作业七年级数学》

1. 方程组$\left\{\begin{array}{l} 3x + 2y = 7,\\ 4x - y = 13\end{array} \right. $的解是 (B)

A.$\left\{\begin{array}{l} x = -1,\\ y = 3\end{array} \right. $
B.$\left\{\begin{array}{l} x = 3,\\ y = -1\end{array} \right. $
C.$\left\{\begin{array}{l} x = -3,\\ y = -1\end{array} \right. $
D.$\left\{\begin{array}{l} x = -1,\\ y = -3\end{array} \right. $

答案： B

2. 下列不是二元一次方程组的是 (C)

A.$\left\{\begin{array}{l} x + y = 4,\\ 2x - y = 4\end{array} \right. $
B.$\left\{\begin{array}{l} 4x + 3y = 6,\\ 2x + 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

3. 若方程$mx - 2y = 3x + 4是关于x,y$的二元一次方程,则$m$的取值范围是 (B)

A.$m ≠ 0$
B.$m ≠ 3$
C.$m ≠ -3$
D.$m ≠ 2$

答案： B

4. 已知$x,y满足方程组\left\{\begin{array}{l} x + m = 4,\\ y - 5 = m,\end{array} \right. 则无论m$取何值,$x,y$恒有关系式 (C)

A.$x + y = 1$
B.$x + y = -1$
C.$x + y = 9$
D.$x + y = -9$

答案： C

5. 一个两位数的十位数字与个位数字之和是7,如果把这个两位数加上45,那么恰好成为把个位数字和十位数字对调后组成的数,那么这个两位数是 (A)

A.16
B.25
C.52
D.61

答案： A

6. 关于$x,y的二元一次方程组\left\{\begin{array}{l} x + y = 2a,\\ x - y = 4a\end{array} \right. 的解是二元一次方程3x - 5y - 28 = 0$的一个解,则$a$等于 (B)

A.3
B.2
C.7
D.6

答案： B

7. 端午节时,王老师用72元钱买了荷包和五彩绳,荷包的个数和五彩绳的条数和为20,其中荷包每个4元,五彩绳每条3元,设王老师买了荷包$x$个,五彩绳$y$条,根据题意,下面列出的方程组正确的是 (B)

A.$\left\{\begin{array}{l} x + y = 20,\\ 3x + 4y = 72\end{array} \right. $
B.$\left\{\begin{array}{l} x + y = 20,\\ 4x + 3y = 72\end{array} \right. $
C.$\left\{\begin{array}{l} x + y = 72,\\ 4x + 3y = 20\end{array} \right. $
D.$\left\{\begin{array}{l} x + y = 72,\\ 3x + 4y = 20\end{array} \right. $

答案： B