数学题求高手``最次高中水平进`
十字相乘法:(ax+b)(cx+d)=
2(x方)+3x+1=6(x方)+x-1=
x*x*x-2x-1=
A方+B方=
(x立方)-3x+2=
(x+1)(x+2)(x+3)(x+4)+x=