(1) (x-6)·(x-3)=x^2-9x+18
(2).(x+1/2)(x-1/3)=x^2+1/6x-1/6
(3)(3x+2)(x+2)=3x^2+6x+2x+4=3x^2+8x+4
(4)(4y-1)·(y-5)=4y^2-20y-y+5=4y^2-21y+5
(5)(x-2)(x 2次方+4) =x^3+4x-2x^2-8=x^3-2x^2+4x-8
(6) (x-y)(x 2次方+xy+y 2次方)=x^3+x^2y+xy^2-x^2y-xy^2-y^3=x^3-y^3.
(1) (x-6)·(x-3)=x^2-9x+18
(2).(x+1/2)(x-1/3)=x^2+1/6x-1/6
(3)(3x+2)(x+2)=3x^2+6x+2x+4=3x^2+8x+4
(4)(4y-1)·(y-5)=4y^2-20y-y+5=4y^2-21y+5
(5)(x-2)(x 2次方+4) =x^3+4x-2x^2-8=x^3-2x^2+4x-8
(6) (x-y)(x 2次方+xy+y 2次方)=x^3+x^2y+xy^2-x^2y-xy^2-y^3=x^3-y^3.