题目内容
下列等式的右边是怎样从左边得到的?
(1)
=
(2)
=
(3)
=
(4)
=
.
(1)
1 |
a+b |
a+b |
a2+2ab+b2 |
(2)
2x(x-y)7 |
4y(y-x)6 |
x(x-y) |
2y |
(3)
(a+b)2 |
a2-b2 |
a+b |
a-b |
(4)
3 |
a+b |
9a(a+b) |
3a(a+b)2 |
(1)分子,分母都乘以(a+b),
=
=
=
;
(2)分子、分母都除以2(x-y)6;
=
=
;
(3)分子,分母都除以(a+b);
=
=
;
(4)分子,分母都乘以3a(a+b),
=
=
.
1 |
a+b |
a+b |
a2+2ab+b2 |
1•(a+b) |
(a+b)(a+b) |
a+b |
a2+2ab+b2 |
(2)分子、分母都除以2(x-y)6;
2x(x-y)7 |
4y(y-x)6 |
2x(x-y)7÷2(x-y)6 |
4y(y-x)6÷2(x-y)6 |
x(x-y) |
2y |
(3)分子,分母都除以(a+b);
(a+b)2 |
a2-b2 |
(a+b)2÷(a+b) |
(a+b)(a-b)÷(a+b) |
a+b |
a-b |
(4)分子,分母都乘以3a(a+b),
3 |
a+b |
3×3a(a+b) |
(a+b)×3a(a+b) |
9a(a+b) |
3a(a+b)2 |
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