Step-by-step explanation:
f(x) = (x + 3)(x - 5)
In a Quadratic curve, the x-coordinate of the vertex is equidistant to the x-intercepts. (If they exist)
In f(x), our x-intercept are x = -3 and x = 5.
=> (-3 + 5)/2 = 1.
Hence the x-value of the vertex is 1.
