Question

已知,a(a-1)-(a²-b)=4,求代数式2／a²+b²-ab的值

Answer 1

a(a－1)－(a²－b)=4

a²－a－a²＋b=4

b－a=4

则：

[(a²＋b²)/2]－ab

=[(a²＋b²)－2ab]/2

=[a²－2ab＋b²]/2

=(a－b)²/2

=(b－a)²/2

=8