(2x-y)的二次方-4(x-2y)(x+2y)

问题描述:

(2x-y)的二次方-4(x-2y)(x+2y)

原式=4x2-4xy+y2-4(x2-4y2)=4x2-4x2-4xy+y2+16y2=17y2-4xy