16．解关于x.y的方程组$\left\{\begin{array}{l}{ax+by=9}\\{3x-cy=-2}\end{array}\right.$时.甲正确的解出$\left\{\begin{——青夏教育精英家教网——

16．解关于x，y的方程组$\left\{\begin{array}{l}{ax+by=9}\\{3x-cy=-2}\end{array}\right.$时，甲正确的解出$\left\{\begin{array}{l}{x=2}\\{y=4}\end{array}\right.$，乙因抄错了c，误解为$\left\{\begin{array}{l}{x=4}\\{y=3}\end{array}\right.$，求a，b，c的值．

15．若方程组$\left\{\begin{array}{l}{3m+n=k}\\{m+3n=2}\end{array}\right.$的解m，n满足m+n＜2，求k的取值范围．

14．$\left\{\begin{array}{l}{a-b+c=2}\\{4a+2b+c=17}\\{5a+4b+c=24}\end{array}\right.$．

13．$\left\{\begin{array}{l}{x+y=4}\\{3x-y=8}\end{array}\right.$．

12．3（2x+7）≥23．

11．a，b，c是直线，且a∥b，b∥c，则a∥c．

10．已知a＜b，用不等号填空：
a+3＜b+3；-$\frac{a}{4}$＞-$\frac{b}{4}$；3-a＞3-b．

9．某种品牌的八宝粥，外包装标明：净含量为330±10g，表明了这罐八宝粥的净含量x的范围是（　　）

8．方程组$\left\{\begin{array}{l}{ax-by=1}\\{bx+ay=7}\end{array}\right.$的解是$\left\{\begin{array}{l}{x=1}\\{y=2}\end{array}\right.$，则（　　）

$\left\{\begin{array}{l}{a=1}\\{b=2}\end{array}\right.$

$\left\{\begin{array}{l}{a=3}\\{b=1}\end{array}\right.$

$\left\{\begin{array}{l}{a=1}\\{b=3}\end{array}\right.$

$\left\{\begin{array}{l}{a=1}\\{b=7}\end{array}\right.$

7．下列方程组中，属于二元一次方程组的是（　　）

$\left\{\begin{array}{l}{x+5y=2}\\{xy=7}\end{array}\right.$

$\left\{\begin{array}{l}{2x+\frac{1}{y}=1}\\{3x-5y=2}\end{array}\right.$

$\left\{\begin{array}{l}{2x=5y}\\{\frac{y}{4}-\frac{z}{3}=\frac{4}{5}}\end{array}\right.$

$\left\{\begin{array}{l}{x-3=9}\\{x+4y=17}\end{array}\right.$

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