《2025年暑假Happy假日七年级理科五四制》

19. (6分)计算:
(1)$\sqrt [3]{-27}+|3-\sqrt {5}|-(\sqrt {9}-\sqrt [3]{8})^{2}+3\sqrt {5}$;
(2)$\sqrt {16}-\sqrt [3]{-8}-\sqrt [3]{1}+\sqrt {1+\frac {9}{16}}$.

答案：
(1)$-1 + 2\sqrt{5}$；
(2)$\frac{25}{4}$

20. (6分)解方程组:
(1)$\left\{\begin{array}{l} 2x+3y=10,\\ 4x+y=5;\end{array}\right. $
$\begin{cases}x=\frac{1}{2}\\y = 3\end{cases}$
(2)$\left\{\begin{array}{l} \frac {x-2}{3}-\frac {y+1}{2}=2,\\ \frac {2x+1}{4}+\frac {y-6}{3}=3.\end{array}\right. $
$\begin{cases}x=\frac{19}{2}\\y = 0\end{cases}$

答案：
(1)$\begin{cases}x=\frac{1}{2}\\y = 3\end{cases}$；
(2)$\begin{cases}x=\frac{19}{2}\\y = 0\end{cases}$