2026年通城学典初中数学运算能手八年级数学上册北师大版第19页答案
一、填空题
1. $2\sqrt{3} × \sqrt{3} =$
6

2. $-\sqrt{20} × \sqrt{\frac{1}{5}} =$
-2

3. $\sqrt{5} × (-\sqrt{3}) =$
$-\sqrt{15}$

4. $\sqrt{18} × \frac{1}{3}\sqrt{2} =$
2

5. $\sqrt{3x} · \sqrt{\frac{1}{3}x} =$
x
$(x ≥ 0)$
6. $\sqrt{\frac{1}{8}} × \sqrt{2} =$
$\frac{1}{2}$

7. $2\sqrt{2} × (-\sqrt{3}) =$
$-2\sqrt{6}$

8. $(-\sqrt{5}) × 2\sqrt{20} =$
-20

答案

1. 6
2. -2
3. $-\sqrt{15}$
4. 2
5. x
6. $\frac{1}{2}$
7. $-2\sqrt{6}$
8. -20
二、计算题
9. $\sqrt{2\dfrac{2}{3}} × (-\sqrt{1\dfrac{1}{2}})$
10. $2\sqrt{24} × (-3\sqrt{6})$
11. $-\sqrt{27} × \sqrt{\dfrac{4}{3}}$
12. $-\sqrt{7} × \sqrt{(-14) × (-2)}$
13. $(-\sqrt{2} × \sqrt{3}) × (-\sqrt{2})$
14. $-\dfrac{1}{6}\sqrt{ab^2} · (-\dfrac{1}{a}\sqrt{ab^2}) \ (a>0)$
15. $2\sqrt{7} × (-\sqrt{3})$
16. $(-4\sqrt{5}) × (-6\sqrt{2})$

答案

9. -2
10. -72
11. -6
12. -14
13. $2\sqrt{3}$
14. $\frac{1}{6}b^2$
15. $-2\sqrt{21}$
16. $24\sqrt{10}$