(X_3)is a factor of xpowerfour_3xcube+2xsquar_2x+5
all those words and improper operators. You apparently want (x-3) to be a factor of
x^4-3x^3+2x^2-2x+5
recall that the Remainder Theorem says that this will be the case if f(3) = 0.
So, evaluate that.