4(-y)的平方-(2y+x)(-x+2y)计算.

问题描述:

4(-y)的平方-(2y+x)(-x+2y)
计算.

4(-y)的平方-(2y+x)(-x+2y)
=4y^2-(4y^2-x^2)
=x^2

4(-y)的平方-(2y+x)(-x+2y)
=4(-y)的平方-(2y+x)(2y-x)
=4y^2-4y^2+x^2
=x^2