First get the equation to equal 0 by subtracting 17 from both sides.
You should have x^2+2x-16=0
Next plug your numbers into the quadratic formula(-b^2+/- the square root of b^2-4ac -all divided by 2a)
The end result should be x=-1+/- the square root of 17 or(if you want the decimal) 3.12310562, -5.12310562
