A(x)2x3 2x3x2 1
B(x)2x2 3x3 x5
Dấu gì?
\(a) A(x)=2x^3-3x^2+2x+1\\ B(x)=3x^3+2x^2-x-5\\ b) A(x)+B(x)=2x^3-3x^2+2x+1+3x^3+2x^2-x-5\\ =(2x^3+3x^3)+(-3x^2+2x^2)+(2x-x)+(1-5)\\ =5x^3-x^2+x-4\\ c) A(x)-B(x)=2x^3-3x^2+2x+1-(3x^3+2x^2-x-5)\\ = 2x^3-3x^2+2x+1-3x^3-2x^2+x+5\\ =(2x^3-3x^3)+(-3x^2-2x^2)+(2x+x)+(1+5)\\ = -x^3-5x^2+3x+6 \)