设a大于b大于0a^2+b^2-6ab=0求a+b/b-a

Question

设a大于b大于0a^2+b^2-6ab=0求a+b/b-a

Answer 1

(a^2+b^2-2ab)-4ab=0 => (a-b)^2 = 4ab
(a^2+b^2+2ab)-8ab=0 => (a+b)^2 = 8ab
又因为a大于b 所以 b-a为负数
所以a+b/b-a = -2^(-2)
即是负根号2