(ax+b)(cx+d)= ac(x方)+(ad+bc)x+bd
2(x方)+3x+1=(2x+1)(x+1)
6(x方)+x-1=(3x-1)(2x+1)
x*x*x-2x-1=?
A方+B方= (a+b)方-2ab
(x立方)-3x+2=?