若a-b=3,ab=2则(a+b)^2=

问题描述:

若a-b=3,ab=2则(a+b)^2=

(a+b)²=a²+b²+2ab
=a²+b²-2ab+4ab
=(a-b)²+4ab
=3²+4x2
=9+8
=17