(-3+y)(3x-y)=() (x-2y)( )=4y平方-X平方 (2m-n)*(2m-n)平方*(2m+n) 8(
2个回答

(-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(