Question 579210
You need to "complete the square":
f(x)=2x²-4x-13
f(x)=2(x²-2x)-13
f(x)=2(x²-2x+1)-13 - 2
f(x)=2(x-1)(x-1) -15
f(x)=2(x-1)^2 -15  (this is what they're looking for)