Yes, the answer is but that is not how you solve a prove question.
There is no point in saying 2/cos x = 2/cos x, because of course that equation is true, and what you have basicly done is rewritten 2sec(x) in the form 2/cos(x).
You should start off on the left, ignoring the right hand side, having only the equation and simplifying/rearranging it to match what is stated.
You must show the steps of how you got that, without the answer of 2sec(x) in the equation:
Continue simplifying/rearranging it to get 2sec(x).
Hint: ( )