Cách `1`:Tính theo hàng ngang `A(x)-B(x)=(2x^4+5x^3-x^2+2x+2)-(-6x^4-5x^3+3x^2-2x+1)` `A(x)-B(x)=2x^4+5x^3-x^2+2x+2+6x^4+5x^3-3x^2+2x-1` `A(x)-B(x)=(2x^4+6x^4)+(5x^3+5x^3)-(x^2+3x^2)+(2x+2x)+(2-1)` `A(x)-B(x)=8x^4+10x^3-4x^2+4x+1` Vậy `A(x)-B(x)=8x^4+10x^3-4x^2+4x+1` Cách `2`:Tính theo cột dọc $\rm \quad\quad\quad A(x)=2x^4+5x^3-x^2+2x+2\\-\\\quad\quad\quad B(x)=-6x^4-5x^3+3x^2-2x+1\\\text{______________________________}\\A(x)-B(x)=8x^4+10x^3-4x^2+4x-1\\ Vậy \ A(x)-B(x)=8x^4+10x^3-4x^2+4x+1$
