(x + a)^2 + b form can be achieved by a method known as completing the square.
Step 1: Divide the b term by 2 and square it
8 / 2 = 4
4^2 = 16
Step 2: Add and subtract 16 from the expression
---Adding 16 creates a perfect square trinomial between x^2 + 8x + 16. But, if we add 16, we also need to subtract it. So, we will subtract 16 from our c term, 14.
x^2 + 8x + 16 + 14 - 16
x^2 + 8x + 16 - 2
Step 3: Factor the perfect square trinomial
(x^2 + 8x + 16) - 2
(x + 4)(x + 4) - 2
(x + 4)^2 - 2
Answer: (x + 4)^2 - 2
Hope this helps! :)