Question

1,Cho f(x)+g(x)=\(6x^4-3x^2-5\)

          f(x)-g(x)=\(4x^4-6x^3+7x^2+8x-9\)

Timf f(x);g(x)

 

Answer 1

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

\(f\left(x\right)-g\left(x\right)=4x^4-6x^3+7x^2+8x-9\)

suy ra:  \(\left[f\left(x\right)+g\left(x\right)\right]+\left[f\left(x\right)-g\left(x\right)\right]=6x^4-3x^2-5+4x^4-6x^3+7x^2+8x-9\)

\(\Leftrightarrow\)\(2f\left(x\right)=10x^4-6x^3+4x^2+8x-14\)

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

       \(g\left(x\right)=6x^4-3x^2-5-f\left(x\right)\)

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