(-3+y)(3x-y)=(-9x+3y+3xy-y^2)
(-3+y)(3x-y)
=-9x+3y+3xy-y^2
(x-2y)(-2y-x)=4y平方-X平方
(4y平方-X平方)/(x-2y)
=(2y+x)(2y-x)/(x-2y)
=-(2y+x)(x-2y)/(x-2y)
=-2y-x
(2m-n)*(2m-n)平方*(2m+n)
=(4m^2-n^2)(2m-n)^2
=(4m^2-n^2)(4m^2-4mn+n^2)
=(4m^2-n^2)[(4m^2+n^2)-4mn]
=16m^4-n^4-4mn(4m^2-n^2)
=16m^4-n^4-16m^3n+4mn^3
8(2分之1x-3)(x+6)
=8(1/2x^2+3x-3x-18)
=8(1/2x^2-18)
=4x^2-144
当a不等于0是,比较大小 -a平方(