数学求救啊~简单哒~

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

x(x-1)-(x-2)(x+2)
=x^2-x-x^2+4
=4-x

108×112
=(100+8)*(100+12)
=10000+1300+96
=11396

(x-3y)(-x-3y)-9y(次数2)
=-(x^2-9y^2)-9y^2
=-x^2

若x+y=6,x-y=5,则x(次数2)-y(次数2)等于（30 ）
解方程：（2x-1）(x+2)-(x-1)(x+1)=(3-x)(-3-x)
2x^2+3x-2-x^2+1=x^2-9
3x=-8
x=-8/3

化简求值：（2x-y）(y+2x)-(2y+x)(2y-x)
=2xy+4x^2-y^2-2xy-4y^2+x^2
=5x^2+3y^2

（x+2y）(x-2y)+(x+1)(1-x)
=x^2-4y^2-(x+1)(x-1)
=x^2-4Y^2-x^2+1
=1-4y^2
=(1+4y)(1-4y)

x(x-1)-(x-2)(x+2)
=x^2-1-x^2+4
=3

108×112
=(110-2)(110+2)
=110^2-4
=12100-4
=12096

(x-3y)(-x-3y)-9y(次数2)
=-[(x-3y)(x+3y)+9y^2]
=-(x^2-9y^2+9y^2)
=-x^2

若x+y=6,x-y=5,则x(次数2)-y(次数2)等于（30）

解方程：（2x-1）(x+2)-(x-1)(x+1)=(3-x)(-3-x)
2x^2+4x-x-2-x^2+1=-(9-x^2)
x^2+3x-1+9-x^2=0
3x+8=0
x