已知a-b=5,ab=6,求2a²+5ab+2b²

问题描述:

已知a-b=5,ab=6,求2a²+5ab+2b²

2a²+5ab+2b²
=2a²-4ab+2b²+9ab
=2(a-b)^2+9ab
=2*5^2+9*6
=2*25+54
=50+54
=104