a(a-1)-(a²-b)=2,求ab-a²+b²/2

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a(a-1)-(a²-b)=2,求ab-a²+b²/2a(a-1)-(a²-b)=2,求ab-a²+b²/2a(a-1)-(a²-b)=2

a(a-1)-(a²-b)=2,求ab-a²+b²/2
a(a-1)-(a²-b)=2,求ab-a²+b²/2

a(a-1)-(a²-b)=2,求ab-a²+b²/2
a(a-1)-(a²-b)=2
a²-a-a²+b=2
-a+b=2
b-a=2
应该是“ab-(a²+b²)/2”吧
要不然算出来不能化简到常数
ab-(a²+b²)/2
=-[(a²+b²)/2-ab]
=-(a²-2ab+b²)/2
=-(a-b)²/2
=-(-2)²/2
=-2

a(a-1)-(a²-b)=2 --> b-a=2
ab-a²+b²/2=a(b-a)+b²/2=2a+b²/2