Question

已知A=1+2x的平方-3x的立方,B=3X的立方-2x的平方-5x-4,x=-125分之64求2A-(A-B)的值

快！!!!!!!!!!!!

Answer 1

解：A＝1+2x^2-3x^3 B=3x^3-2x^2-5x-4 x=-64/125
2A-(A-B)=2A-A+B=A+B
=1+2x^2-3x^3 + 3x^3-2x^2-5x-4
=1-5x-4
=-5x-3
=-5×(-64/125)-3
=64/25-3
=-11/25