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1. 计算.
(1) $3^2 ÷ (-3)^2 + \left| \frac{1}{6} \right| × (-6) + \sqrt{49}$；
(2) $( \frac{1}{2} )^2 + ( \frac{1}{3} )^{-1} - \sqrt[3]{8} - (-2)^2$.
(1) $3^2 ÷ (-3)^2 + \left| \frac{1}{6} \right| × (-6) + \sqrt{49}$；
(2) $( \frac{1}{2} )^2 + ( \frac{1}{3} )^{-1} - \sqrt[3]{8} - (-2)^2$.
答案
(1)7.
(2)$-2\dfrac{3}{4}$.
(2)$-2\dfrac{3}{4}$.
2. 解下列方程组.
(1) $\begin{cases}\dfrac{x}{2}+\dfrac{y}{3}=3, \\ $
$ \\ \dfrac{x}{3}-\dfrac{y}{3}=2;\end{cases}$
(2) $\begin{cases}0.5x - y = 1, \\ x - 4y = 0;\end{cases}$
(3) $\begin{cases}23x +17y=63, \\17x +23y=57;\end{cases}$
(4) $\begin{cases}x -2=2(y -1), \\2(x -2)+(y -1)=5;\end{cases}$
(5) $\begin{cases}2009x -2011y=2007, \\2008x -2010y=2006;\end{cases}$
(6) $\begin{cases}\dfrac{m}{3}-\dfrac{n}{4}=1, \\ $
$ \\ \dfrac{m -3}{2}-\dfrac{n -1}{3}=\dfrac{1}{2}.\end{cases}$
(1) $\begin{cases}\dfrac{x}{2}+\dfrac{y}{3}=3, \\ $
$ \\ \dfrac{x}{3}-\dfrac{y}{3}=2;\end{cases}$(2) $\begin{cases}0.5x - y = 1, \\ x - 4y = 0;\end{cases}$
(3) $\begin{cases}23x +17y=63, \\17x +23y=57;\end{cases}$
(4) $\begin{cases}x -2=2(y -1), \\2(x -2)+(y -1)=5;\end{cases}$
(5) $\begin{cases}2009x -2011y=2007, \\2008x -2010y=2006;\end{cases}$
(6) $\begin{cases}\dfrac{m}{3}-\dfrac{n}{4}=1, \\ $
$ \\ \dfrac{m -3}{2}-\dfrac{n -1}{3}=\dfrac{1}{2}.\end{cases}$答案
(1)$\begin{cases}x=6,\\y=0.\end{cases}$
(2)$\begin{cases}x=4,\\y=1.\end{cases}$
(3)$\begin{cases}x=2,\\y=1.\end{cases}$
(4)$\begin{cases}x=4,\\y=2.\end{cases}$
(5)$\begin{cases}x=2,\\y=1.\end{cases}$
(6)$\begin{cases}m=6,\\n=4.\end{cases}$
(2)$\begin{cases}x=4,\\y=1.\end{cases}$
(3)$\begin{cases}x=2,\\y=1.\end{cases}$
(4)$\begin{cases}x=4,\\y=2.\end{cases}$
(5)$\begin{cases}x=2,\\y=1.\end{cases}$
(6)$\begin{cases}m=6,\\n=4.\end{cases}$
