计算:(x-2y)的平方-(x+2y)(x-2y)=
问题描述:
计算:(x-2y)的平方-(x+2y)(x-2y)=
答
(x-2y)^2-(x+2y)(x-2y)=【x^2-4xy+[2y]^2】-【x^2-[2y]^2】=-4xy+[2y]^2*2
答
=X的平方-4XY+4Y的平方-(X的平方-4Y的平方)
=X的平方-4XY+4Y的平方-X的平方+4Y的平方
=8y的平方-4XY
答
(x-2y)的平方-(x+2y)(x-2y)
=X的平方-4Xy+4y的平方-X的平方+4y的平方
=8y的平方-4Xy
=4y(2y-X)
答
(x-2y)的平方-(x+2y)(x-2y)
=x^2-4xy+4y^2-(x^2-4y^2)
=x^2-4xy+4y^2-x^2+4y^2
=8y^2-4xy