如上题已知a+b=6,ab=4,求(a-b)²的值,我求教懂我,

问题描述:

如上题已知a+b=6,ab=4,求(a-b)²的值,我求教懂我,

答:
a+b=6,ab=4
(a-b)²=(a+b)²-4ab
=6²-4*4
=36-16
=20
所以:(a-b)²=20