Evaluating a polynomial is like evaluating any other expression. We substitute the given value(s) for each and every variable. Then we do the necessary plusing and minusing to find an answer. If you come across a polynomial that involves only subtraction, you may be a little nonplussed.
Evaluate the polynomial 4x2 - 2x + 7 for x = 3.
We substitute 3 for every occurrence of x to get 4(3)2 - 2(3) + 7 and simplify to 37.
That really wasn't as bad as you were expecting, was it?