Question

I am so confused can someone please explain to me how to do this?
Using the completing-the-square method, rewrite f(x) = x2 + 10x + 7 in vertex form.

f(x) = (x + 5)2 − 18
f(x) = (x + 10)2 + 25
f(x) = (x + 5)2 + 7
f(x) = (x + 5)2