已知2x+y=3,x-2y=5,求2x^2-3xy-2y^2的值?

问题描述:

已知2x+y=3,x-2y=5,求2x^2-3xy-2y^2的值?

2x^2-3xy-2y^2
=(x-2y)(2x+y)
=3*5=15