已知A=x3-2x2+x-4,B=2x3-5x+3,计算A+B=______．

更新时间：2022-06-13 07:05:50 95次访问

A+B

=(x³-2x²+x-4)+(2x³-5x+3)

=(x³+2x³)-2x²+(x-5x)+(-4+3)

=3x³-2x²-4x-1

//

4x²-[7x²-5x-3(1-2x+x²)]

=4x²-7x²+5x+3(1-2x+x²)

=-3x²+5x+(3-6x+3x²)

=(-3x²+3x²)+(5x-6x)+3

=-x+3

3x3-2x2-4x-1