Evaluating $2x^3+2x^2-7x+72$ where $x= \frac{3-5i}{2} $ So I have to find the value of  : 
$$2x^3+2x^2-7x+72$$ at $$x= \frac{3-5i}{2} $$
Where $i$ stands for $\sqrt{-1}$.
I know the obvious approach would be to substitute the value of $x$ in the equation, but the equation gets extremely messy in that process. Is there any easier or quicker approach for the sum. 
P.s. The answer is $4$.

You have $\frac{3-5i}{2}$ is the solution of $2x^2-6x+17 = 0$.
Then, $$2x^3 + 2x^2-7x+72 = x(2x^2-6x+17) + 4(2x^2-6x+17) + 4 = 4.$$
