If $f (x) +f'(x) = x^3+5x^2+x+2$ then find $f (x)$ 
If  $f (x) +f'(x) = x^3+5x^2+x+2$  then  find $f(x)$.

$f'(x)$ is the first derivative of $f (x)$.
I have no idea about this question, please help me. 

Assume a polynomial function of the form $f(x)=ax^3+bx^2+cx+d$ then $f^{'}(x)=3ax^2+2bx+c$
Thus the equations becomes $ax^3+(3a+b)x^2+(c+2b)x+d+c=x^3+5x^2+x+2$.
Now you can compare the coefficients to get the solution.
