BÀI 1
a) P(x) + Q(x)
=\(\left(2x^3+x^2-x+1\right)+\left(x^3-x^2-x+1\right)\)
=\(2x^3+x^2-x+1+x^3-x^2-x+1\)
=\(\left(2x^3+x^3\right)+\left(x^2-x^2\right)+\left(-x-x\right)+\left(1+1\right)\)
=\(3x^3-2x+2\)
b) P(x) - Q(x)
=\(2x^3+x^2-x+1-x^3-x^2-x+1\)
=\(\left(2x^3-x^3\right)+\left(x^2-x^2\right)+\left(-x-x\right)+\left(1+1\right)\)
=\(x^3-2x+2\)