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9. 矩形的长是$3\sqrt{35}$，宽为$\sqrt{20}$，则它的面积是
$30\sqrt{7}$
.答案
9. $30\sqrt{7}$
10. 计算：$|\sqrt{8} - π| + |\sqrt{2} - 2| = \underline{\hspace{15cm}}.$
答案
10. $π+2-3\sqrt{2}$
11. 若$a＜1$，化简$\sqrt{(a - 1)^2} - 1=$
$-a$
.答案
11. $-a$
12. 计算:
(1) $\sqrt{1\dfrac{1}{3}} ÷ \sqrt{2\dfrac{2}{3}} × \sqrt{1\dfrac{3}{5}}$；
(2) $(\sqrt{3}-\sqrt{12}) × 2\sqrt{3} +5\sqrt{2}-\sqrt{8}$；
(3) $(π-1)^0 + (-\dfrac{1}{2})^{-1} + |5-\sqrt{27}| -3\sqrt{3}$；
(4) $(4\sqrt{2}-\sqrt{6}) ÷ 2\sqrt{2}$；
(5) $(2\sqrt{3}+3\sqrt{2})(2\sqrt{3}-3\sqrt{2})-(5\sqrt{3}+2\sqrt{5})^2$；
(6) $(3\sqrt{18} + \dfrac{1}{5}\sqrt{50} - 4\sqrt{\dfrac{1}{2}}) ÷ \sqrt{32}$。
(1) $\sqrt{1\dfrac{1}{3}} ÷ \sqrt{2\dfrac{2}{3}} × \sqrt{1\dfrac{3}{5}}$；
(2) $(\sqrt{3}-\sqrt{12}) × 2\sqrt{3} +5\sqrt{2}-\sqrt{8}$；
(3) $(π-1)^0 + (-\dfrac{1}{2})^{-1} + |5-\sqrt{27}| -3\sqrt{3}$；
(4) $(4\sqrt{2}-\sqrt{6}) ÷ 2\sqrt{2}$；
(5) $(2\sqrt{3}+3\sqrt{2})(2\sqrt{3}-3\sqrt{2})-(5\sqrt{3}+2\sqrt{5})^2$；
(6) $(3\sqrt{18} + \dfrac{1}{5}\sqrt{50} - 4\sqrt{\dfrac{1}{2}}) ÷ \sqrt{32}$。
答案
12. (1) $\dfrac{2\sqrt{5}}{5}$.
(2) $3\sqrt{2}-6$.
(3) $-6$.
(4) $2-\dfrac{\sqrt{3}}{2}$.
(5) $-101-20\sqrt{15}$.
(6) $2$.
(2) $3\sqrt{2}-6$.
(3) $-6$.
(4) $2-\dfrac{\sqrt{3}}{2}$.
(5) $-101-20\sqrt{15}$.
(6) $2$.
