题目内容
计算:(1)
| 7 |
| 7 |
| 2 |
| 3 |
(3)
| 2000 |
| (-16)×9×(-81) |
分析:根据二次根式的乘法法则计算,注意使用公式时,被开方数为非负数.
解答:解:(1)
×
=
=7;
(2)
×(-
)=-
=-
;
(3)
=
=
×
=20
;
(4)
=
=
×
×
=4×3×9=108.
| 7 |
| 7 |
| 7×7 |
(2)
| 2 |
| 3 |
| 2×3 |
| 6 |
(3)
| 2000 |
| 400×5 |
| 400 |
| 5 |
| 5 |
(4)
| (-16)×9×(-81) |
| 16×9×81 |
| 16 |
| 9 |
| 81 |
点评:主要考查了二次根式的乘法运算.乘法法则
•
=
(a≥0,b≥0).
| a |
| b |
| ab |
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