已知1/a-1/b=3.求(2a+3ab-2b)/(a+2ab-b)
问题描述:
已知1/a-1/b=3.求(2a+3ab-2b)/(a+2ab-b)
答
1/a-1/b=3,可知b-a=3ab
(2a+3ab-2b)/(a+2ab-b)
=[-2(b-a)+3ab]/[-(b-a)+2ab]
=-3ab/(-ab)
=3
答
1/a-1/b=3.
两边同乘ab得
b-a=3ab
则a-b=-3ab
(2a+3ab-2b)/(a+2ab-b)
原式=2(a-b)+3ab/(a-b)+2ab
把a-b=-3ab代入得
-6ab+3ab/-3ab+2ab
=-3/-1=3
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