Question

已知A＝－2x^2,B=x^2－3x－1,C=－x+1,求A×B＋A×C,(2)A×C－B,(3)2分之1AB＋B＋A

Answer 1

(1)A×B＋A×C

=－2x^2*(x^2－3x－1)－2x^2*(－x+1)

=-2x^4+6x^3+2x^2+2x^3-2x^2

==-2x^4+8x^3

(2)A×C－B

=－2x^2*(－x+1)-(x^2－3x－1)

=2x^3-2x^2-x^2+3x+1

=2x^3-3x^2+3x+1

(3)2分之1AB＋B＋A

=(1/2)(－2x^2)*(x^2－3x－1)+x^2－3x－1－2x^2

=-x^4+3x^3+x^2+x^2－3x－1－2x^2

=-x^4+3x^3－3x－1