初中数学解二元一次方程组选择题

已知是方程组的解，则的值是（  ）

A．－1

B．2

C．3

D．4

方程组 $\left\{\begin{array}{c}x+y=5\\ x-y=3\end{array}\right.$ 的解是 $($ 　　 $)$

A．

$\left\{\begin{array}{c}x=2\\ y=3\end{array}\right.$

B．

$\left\{\begin{array}{c}x=3\\ y=2\end{array}\right.$

C．

$\left\{\begin{array}{c}x=4\\ y=1\end{array}\right.$

D．

$\left\{\begin{array}{c}x=1\\ y=4\end{array}\right.$

方程组 $\left\{\begin{array}{c}x+y=2\\ 3x+y=4\end{array}\right.$ 的解是 $($ 　　 $)$

A．

$\left\{\begin{array}{c}x=0\\ y=2\end{array}\right.$

B．

$\left\{\begin{array}{c}x=1\\ y=1\end{array}\right.$

C．

$\left\{\begin{array}{c}x=2\\ y=-2\end{array}\right.$

D．

$\left\{\begin{array}{c}x=3\\ y=-3\end{array}\right.$

已知关于 $x$， $y$的二元一次方程组 $\left\{\begin{array}{c}2\mathit{ax}+\mathit{by}=3\\ \mathit{ax}-\mathit{by}=1\end{array}\right.$的解为 $\left\{\begin{array}{c}x=1\\ y=-1\end{array}\right.$，则 $a-2b$的值是 $($　　 $)$

A． $-2$B．2C．3D． $-3$

方程组 $\frac{x}{3}=\frac{y}{2}=x+y-4$的解是 $($　　 $)$

A． $\left\{\begin{array}{c}x=-3\\ y=-2\end{array}\right.$B． $\left\{\begin{array}{c}x=6\\ y=4\end{array}\right.$C． $\left\{\begin{array}{c}x=2\\ y=3\end{array}\right.$D． $\left\{\begin{array}{c}x=3\\ y=2\end{array}\right.$

用加减消元法解二元一次方程组 $\left\{\begin{array}{c}x+3y=4,①\\ 2x-y=1ㅤ②\end{array}\right.$时，下列方法中无法消元的是 $($　　 $)$

A．① $\times 2-$②B．② $\times (-3)-$①C．① $\times (-2)+$②D．① $-$② $\times 3$

已知 $a$ ， $b$ 是等腰三角形的两边长，且 $a$ ， $b$ 满足 $\sqrt{2a-3b+5}+{(2a+3b-13)}^2=0$ ，则此等腰三角形的周长为 $($ 　　 $)$

A．

8

B．

6或8

C．

7

D．

7或8

已知方程组 $\left\{\begin{array}{c}2x+y=4\\ x+2y=1\end{array}\right.$，则 $x-y$的值为 $($　　 $)$

A． $\frac{5}{3}$B．2C．3D． $-2$

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

A． $\left\{\begin{array}{c}x=1\\ y=2\end{array}\right.$B． $\left\{\begin{array}{c}x=-3\\ y=-2\end{array}\right.$C． $\left\{\begin{array}{c}x=2\\ y=0\end{array}\right.$D． $\left\{\begin{array}{c}x=3\\ y=-1\end{array}\right.$

已知 $a$， $b$满足方程组 $\left\{\begin{array}{c}3a+2b=4\\ 2a+3b=6\end{array}\right.$，则 $a+b$的值为 $($　　 $)$

A．2B．4C． $-2$D． $-4$

若方程组 $\left\{\begin{array}{cc}2x+y=1-3k& ①\\ x+2y=2& ②\end{array}\right.$的解满足 $x+y=0$，则 $k$的值为 $($　　 $)$

A． $-1$B．1C．0D．不能确定

二元一次方程组 $\left\{\begin{array}{c}x+y=6\\ x-3y=-2\end{array}\right.$的解是 $($　　 $)$

A． $\left\{\begin{array}{c}x=5\\ y=1\end{array}\right.$B． $\left\{\begin{array}{c}x=4\\ y=2\end{array}\right.$C． $\left\{\begin{array}{c}x=-5\\ y=-1\end{array}\right.$D． $\left\{\begin{array}{c}x=-4\\ y=-2\end{array}\right.$

若 $|3x-2y-1|+\sqrt{x+y-2}=0$，则 $x$， $y$的值为 $($　　 $)$

A． $\left\{\begin{array}{c}x=1\\ y=4\end{array}\right.$B． $\left\{\begin{array}{c}x=2\\ y=0\end{array}\right.$C． $\left\{\begin{array}{c}x=0\\ y=2\end{array}\right.$D． $\left\{\begin{array}{c}x=1\\ y=1\end{array}\right.$

二元一次方程组 $\left\{\begin{array}{c}x+y=5\\ 2x-y=4\end{array}\right.$的解为 $($　　 $)$

A． $\left\{\begin{array}{c}x=1\\ y=4\end{array}\right.$B． $\left\{\begin{array}{c}x=2\\ y=3\end{array}\right.$C． $\left\{\begin{array}{c}x=3\\ y=2\end{array}\right.$D． $\left\{\begin{array}{c}x=4\\ y=1\end{array}\right.$

二元一次方程组 $\left\{\begin{array}{c}x+y=2\\ 2x-y=4\end{array}\right.$的解是 $($　　 $)$

A． $\left\{\begin{array}{c}x=0\\ y=2\end{array}\right.$B． $\left\{\begin{array}{c}x=2\\ y=0\end{array}\right.$C． $\left\{\begin{array}{c}x=3\\ y=-1\end{array}\right.$D． $\left\{\begin{array}{c}x=1\\ y=1\end{array}\right.$