Question

Cho hai đa thức P(x)= -2x⁴-7x²+3x và Q(x)= 5x³-3x²+4x-6 

Tính P(x) + Q(x) và P(x) - Q(x)

Answer 1

\(P\left(x\right)+Q\left(x\right)=\left(-2x^4-7x^2+3x\right)+\left(5x^3-3x^2+4x-6\right)\)

\(=-2x^4-7x^2+3x+5x^3-3x^2+4x-6\)

\(=-2x^4+5x^3+\left(-7x^2-3x^2\right)+\left(3x+4x\right)-6\)

\(=-2x^4+5x^3-10x^2+7x-6\)

\(P\left(x\right)-Q\left(x\right)=\left(-2x^4-7x^2+3x\right)-\left(5x^3-3x^2+4x-6\right)\)

\(=-2x^4-7x^2+3x-5x^3+3x^2-4x+6\)

\(=-2x^4-5x^3+\left(-7x^2+3x^2\right)+\left(3x-4x\right)+6\)

\(=-2x^4-5x^3-4x^2-x+6\)