+128475 9x^2 + 18x + 7
If you know Calculus, you can find this quickly, but, if not, the x value that will minimize this is given by
-b / (2a) where b = 18 and a = 9 .......so
x = -18 / ( 2 * 9) = -18 / 18 = -1
And since this is a parabola that turns upward, this is the x value of the vertex, i.e., the x value that minimizes the function
