已知a+b=6,ab=4,求(a-b)^2的值
问题描述:
已知a+b=6,ab=4,求(a-b)^2的值
答
(a-b)²
=a²-2ab+b²
=(a²+2ab+b²)-4ab
=(a+b)²-4ab
=6²-4×4
=36-16
=20