What is f (x) = 2x2 + 28x - 5 written in vertex form?

To convert a quadratic from y = ax 2 + bx + c form to vertex form, y = a (x - h) 2 + k, you use the process of completing the square. We do as follows:

f (x) = 2x^2 + 28x - 5

f (x) = 2 (x^2 + 14x) - 5

f (x) = 2 (x^2 + 14x + 49) - 5 - 98

f (x) = 2 (x + 7) ^2 - 103

Hope this answers the question. Have a nice day.