\(P\left(x\right)=2x^3-2x+x+x^2-x^3+x+2\)
\(P\left(x\right)=\left(2x^3-x^3\right)+x^2+\left(-2x+x\right)+2\)
\(P\left(x\right)=x^3+x^2-x+2\)
\(Q\left(x\right)=3x^3-4x^2+3x-4x-4x^3+5x^2+1\)
\(Q\left(x\right)=\left(3x^3-4x^3\right)+\left(-4x^2+5x^2\right)+\left(3x-4x\right)+1\)
\(Q\left(x\right)=-x^3+x^2-x+1\)
a) \(M\left(x\right)=P\left(x\right)+Q\left(x\right)=\left(x^3+x^2-x+2\right)+\left(-x^3+x^2-x+1\right)\)
\(M\left(x\right)=x^3+x^2-x+2+-x^3+x^2-x+1\)
\(M\left(x\right)=\left(x^3-x^3\right)+\left(x^2+x^2\right)+\left(-x-x\right)+\left(2+1\right)\)
\(M\left(x\right)=2x^2-2x+3\)
N(x)=P(x)-Q(x) ... tt cộng thôi ==
b) Theo nghiệm ta có: 2x2-2x+3=0
=> 2x2-2x=-3
=> x vô nghiệm