Question

4. Tính hiệu P(x)-Q(x) bằng hai cách ,trong đó: P(X)=6X³ +8x²+5x-2; Q(x)=-9x³ +6x² + 3+2x

Answer 1

P(x)-Q(x)

=6x^3+8x^2+5x-2+9x^3-6x^2-2x-3

=15x^3+2x^2+2x-5

Answer 2

\(P\left(x\right)-Q\left(x\right)=\left(6x^3+8x^2+5x-2\right)-\left(-9x^3+6x^2+3+2x\right)\)

                       \(=6x^3+8x^2+5x-2+9x^3-6x^2-3-2x\)

                       \(=6x^3+9x^3+8x^2-6x^2+5x-2x-2-3\)

                       \(=15x^3+2x^2+3x-5\)