You can
put this solution on YOUR website! First of all, please post in a relevant category. You posted this under Quadratic Equations but it is not a quadratic. I have changed the category to an appropriate one: Polynomials.
It is the Remainder Theorem which allows us to divide a polynomial in order to find the value of the polynomial for some value of x. To find the value of f(-2) we will divide by (x-(-2)). Using synthetic division to divide:
-2 | -16 18 -1 2
----- 32 -100 202
-------------------
-16 50 -101 204
The remainder is in the lower right corner. The Remainder theorem tells us that the remainder will be f(-2). So f(-2) = 204