已知(a-b)/ab=4,则a-2ab-b/2a-2b+7ab=?

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已知(a-b)/ab=4,则a-2ab-b/2a-2b+7ab=?
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已知(a-b)/ab=4,则a-2ab-b/2a-2b+7ab=?
已知(a-b)/ab=4,则a-2ab-b/2a-2b+7ab=?

已知(a-b)/ab=4,则a-2ab-b/2a-2b+7ab=?
因为 (a - b)/ab = 4
所以 a - b = 4ab
所以 (a - 2ab - b)/(2a - 2b + 7ab)
= [(a - b) - 2ab]/[2(a - b) + 7ab]
= (4ab - 2ab)/(8ab + 7ab)
= 2ab/15ab
= 2/15

(a-b)/ab=4
∴a-b=4ab

a-2ab-b/2a-2b+7ab
=[(a-b)-2ab]/[2(a-b)+7ab]
=(4ab-2ab)/(8ab+7ab)
=2/15

(a-b)/ab=4
a-b=4ab
(a-2ab-b)/(2a-2b+7ab)
=[(a-b)-2ab]/[2(a-b)+7ab]
=(4ab-2ab)/(8ab+7ab)
=2ab/15ab
=2/15

a-b=4ab , (a-b)-2ab=4ab-2ab=2ab ,2a-2b+7ab=2*4ab+7ab=15ab ,原式=2ab/15ab=2/15

思路:把a-b用ab代替;
由(a-b)/ab=4得:a-b=4ab,
所以:a-2ab-b/2a-2b+7ab=[(a-b)-2ab]/[2(a-b)+7ab]=(4ab-2ab)/(8ab+7ab)=2ab/15ab=2/15