已知a²+3a-5=0,b²+3b-5=0,求b²/a+a²/b的值
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已知a²+3a-5=0,b²+3b-5=0,求b²/a+a²/b的值
已知a²+3a-5=0,b²+3b-5=0,求b²/a+a²/b的值
已知a²+3a-5=0,b²+3b-5=0,求b²/a+a²/b的值
a^2+3a-5=0,b^2+3b-5=0
所以可以把a、不看作是方程x²+3x-5=0的两个根.
故a+b=-3,ab=-5
所以(b^2)/(a)+(a^2)/(b)
=(a³+b³)/ab
=(a+b)(a²-ab+b²)/ab
=(a+b)[(a+b)²-3ab]/ab
=-3(9+15)/-5
=72/5