已知1/a - 1/b=4,则(a-2ab-b)/(2a-2b+7ab)的值等于A.6 B.-6 C.2/15 D.-2/7
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![已知1/a - 1/b=4,则(a-2ab-b)/(2a-2b+7ab)的值等于A.6 B.-6 C.2/15 D.-2/7](/uploads/image/z/14557086-54-6.jpg?t=%E5%B7%B2%E7%9F%A51%2Fa+-+1%2Fb%3D4%2C%E5%88%99%28a-2ab-b%29%2F%282a-2b%2B7ab%29%E7%9A%84%E5%80%BC%E7%AD%89%E4%BA%8EA.6+B.-6+C.2%2F15+D.-2%2F7)
已知1/a - 1/b=4,则(a-2ab-b)/(2a-2b+7ab)的值等于A.6 B.-6 C.2/15 D.-2/7
已知1/a - 1/b=4,则(a-2ab-b)/(2a-2b+7ab)的值等于
A.6 B.-6 C.2/15 D.-2/7
已知1/a - 1/b=4,则(a-2ab-b)/(2a-2b+7ab)的值等于A.6 B.-6 C.2/15 D.-2/7
1/a - 1/b=4
(b-a)/ab=4
b-a=4ab
(a-2ab-b)/(2a-2b+7ab)=
-(b-a+2ab)/-(2(b-a)-7ab)=
(4ab+2ab)/(8ab-7ab)=
6ab/ab=6
OK