Question

多项式与多项式的乘法3-2(x+1)(x-2)-x^2+3(x+2)(x-3)求详细过程 -后面2（x+1)怎么变额?括

Answer 1

2(x+1)(x-2)=2(x^2-2x+x-2)=2x^2-2x-4

3(x+2)(x-3)=3(x^2-3x+2x-6)=3x^2-3x-18

原式=3-（2x^2-2x-4）-x^2+(3x^2-3x-18)

=3-2x^2+2x+4-x^2+3x^2-3x-18

=-x-11