MATHEMATICAL INDUCTION

When n=1
L.H.S. = 2^1 =2 = (2x1) =R.H.S.
Assume n=k is true, i.e., 2^k >= 2k
When n=k+1
L.H.S = 2^(k+1) = 2 x 2^k >= 2 x 2k =4k = 2k + 2k >= 2k + 2 = 2(k+1) = R.H.S.