Giải thích các bước giải:
a) `A(x) = 3x^2 + 5x^3 + x - 2x^2 - x^3 + 1 - 4x^3 - 2x - 3`
`=(5x^3- 4x^3- x^3)+ (3x^2 - 2x^2) + (x - 2x) + 1 - 3`
`=x^2-x-2`
b) `A(x)=B(x)`
`<=>x^2-x-2=2x-2`
`<=>x^2-x-2-2x+2=0`
`<=>x^2-3x=0`
`<=>x(x-3)=0`
`=>`\(\left[ \begin{array}{l}x=0\\x-3=0\end{array} \right.\) `=>`\(\left[ \begin{array}{l}x=0\\x=3\end{array} \right.\)