初一数学计算题目..在线等(过程写详细点)

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

(2).(2a+1)^2-(1-2a)^2
=[(2a+1)+(1-2a)][(2a+1)-(1-2a)]
=(2a+1+1-2a)(2a+1-1+2a)
=2*4a
=8a

(3).(3x-y)^2-(2x+y)^2+5x(y-x)
=[(3x-y)+(2x+y)][(3x-y)-(2x+y)]+5x(y-x)
=(3x-y+2x+y)(3x-y-2x-y)+5x(y-x)
=5x*(x-2y)+5x(y-x)
=5x(x-2y+y-x)
=5x(-y)
=-5xy

1、(x-2y-(x+2y))(x+2y)
=-4y(x+2y)

2(2a+1-(1-2a))
=2*4a
=8a
(x+2y)(x-2y-x-2y)=(x+2y)(-4y)=-4xy-8xy;

(2a+1+1-2a)(2a+1-1+2a)=2(4a)=8a;

(3x-y+2x+y)(3x-y-2x-y)+5x(y-x)=5x(x-2y)+5x(y-x)=5x(y-x+x-2y)=-5xy

1).(x-2y)(x+2y)-(x+2y)^2
=(x+2y)[(x-2y)-(x+2y)]（提取公因式）
=(x+2y)*(-4y)
=-4y(x+2y)
2).(2a+1)^2-(1-2a)^2 （平方差公式）
=(2a+1+1-2a)(2a+1-1+2a)
=2(4a)
=8a
3).(3x-y)^2-(2x+y)^2+5x(y-x) (先整理，再分解)
=9x^2-6xy+y^2-(4x^2+4xy+y^2)+5xy-5x^2
=-5xy

1、(x-2y-(x+2y))(x+2y)
=-