Select the x-coordinate of the vertex of the parabola defined by the function f(x) = -9x 2 + 7x + 1

Question

Select the x-coordinate of the vertex of the parabola defined by the function f(x) = -9x 2 + 7x + 1

Answer 1

If f(x) = Ax² + Bx + C and A ≠ 0, then the graph of f is a parabola.  The x - coordinate of the vertex is -B/(2A).  So, for the given parabola the 

x - coordinate of the vertex is -7/((2)(-9)) = 7/18.