Solve by completing the square

2f^2+56f=-34

To solve by completing the square, first divide the equation by 2 to simplify:

f^2 + 28f = -17

Next, take half of the coefficient of f (28) and square it:

28/2 = 14
14^2 = 196

Add and subtract 196 inside the parentheses on the left side of the equation:

f^2 + 28f + 196 - 196 = -17

Now, rewrite the equation with a perfect square trinomial:

(f + 14)^2 - 196 = -17

Add 196 to both sides of the equation:

(f + 14)^2 = 179

Take the square root of both sides:

f + 14 = ± √179

Now, isolate f:

f = -14 ± √179