Question

整式计算

（x+2y-1）（x-2y+1）-（x-2y-1）^2

Answer 1

你好！！
具体解法如下：
（x+2y-1）（x-2y+1）-（x-2y-1）^2
=[x+(2y-1)}{x-(2y-1)]-[x-(2y+1)]^2
=x^2-(2y-1)^2-x^2+2x(2y+1)-(2y+1)^2
=-(2y-1)^2+2x(2y+1)-(2y+1)^2
=-4y^2+4y-1+4xy+2x-4y^2-4y-1
=-8y^2-2+4xy+2x

Answer 2

（x+2y-1）（x-2y+1）-（x-2y-1）^2
=[x+(2y-1)}{x-(2y-1)]-[x-(2y+1)]^2
=x^2-(2y-1)^2-x^2+2x(2y+1)-(2y+1)^2
=-(2y-1)^2+2x(2y+1)-(2y+1)^2
=-4y^2+4y-1+4xy+2x-4y^2-4y-1
=-8y^2-2+4xy+2x

Answer 3

（x+2y-1）（x-2y+1）-（x-2y-1）^2
=[x+(2y-1)][x-(2y-1)]-(x-2y-1)^2
=x^2-(2y-1)^2-[x-(2y+1)]^2
=x^2-(4y^2-4y+1)-[x^2-2x(2y-1)+(2y+1)^2]
=x^2-4y^2+4y-1-x^2+4xy-2x-4y^2-4y-1
=-8y^2+4xy-2-2x.

Answer 4

（x+2y-1）（x-2y+1）-（x-2y-1）^2
= x^2 - (2y-1)^2 - (x^2 + 4y^2 + 1 - 4xy - 2x + 4y)
= x^2 - 4y^2 + 4y - 1 - x^2 - 4y^2 - 1 + 4xy + 2x - 4y
= -8y^2 - 2 + 4xy + 2x