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

f (x) = 2 (x^2 + 14x + ) - 5 2 is taken out of first 2 terms.

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

2 steps

Inside the brackets: Linear term's coefficient (14) divided by 2 and squared Outside the brackets: (14/2) ^2 multiplied by 2 and subtract so that there is no change in the value of the quadratic.

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

The graph is of the original quadratic.