Question

Cho 2 đa thức : P(x) = 3+2x^2-5x-1+5x^3+7 Q(x)= -9x+5x^3+x^2+2+x a) Thu gọn và sắp xếp b)Tính f(x) =P(x)+Q(x)

Answer 1

a) \(P\left(x\right)=3+2x^2-5x-1+5x^3+7\)

\(=5x^3+2x^2-5x+\left(3-1+7\right)\)

\(=5x^3+2x^2-5x+9\)

\(Q\left(x\right)=-9x+5x^3+x^2+2+x\)

\(=5x^3+x^2+\left(-9x+x\right)+2\)

\(=5x^3+x^2-8x+2\)

b) \(f\left(x\right)=P\left(x\right)+Q\left(x\right)\)

\(=\left(5x^3+2x^2-5x+9\right)+\left(5x^3+x^2-8x+2\right)\)

\(=5x^3+2x^2-5x+9+5x^3+x^2-8x+2\)

\(=\left(5x^3+5x^3\right)+\left(2x^2+x^2\right)+\left(-5x-8x\right)+\left(9+2\right)\)

\(=10x^3+3x^2-13x+11\)