当(a+b)²+2取最小值时,求a³b+(2a²b²-ab)-(5a²b²+4a³b-8)-a²求大神破啊+1008611!
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当(a+b)²+2取最小值时,求a³b+(2a²b²-ab)-(5a²b²+4a³b-8)-a²求大神破啊+1008611!
当(a+b)²+2取最小值时,求a³b+(2a²b²-ab)-(5a²b²+4a³b-8)-a²
求大神破啊+1008611!
当(a+b)²+2取最小值时,求a³b+(2a²b²-ab)-(5a²b²+4a³b-8)-a²求大神破啊+1008611!
(a+b)²≥0,要想(a+b)²+2取最小值时必须是(a+b)²取最小值,即
(a+b)²=0,所以a+b=0
a³b+(2a²b²-ab)-(5a²b²+4a³b-8)-a²
=a³b+2a²b²-ab-5a²b²-4a³b+8-a²
=﹣3a³b-3a²b²-ab-a²+8
=﹣3a²b(a+b)-a(a+b)+8
=0-0+8
=8
好像没有吧,a和b可以是负数吗