As you said the base case is proven.
ie k^2<2^k for k>=5
For the induction, let us assume that
k^2<2^k
We need to prove that
(k+1)^2<2^(k+1)
(k+1)^2 = k^2 + 2k + 1 < 2^k + 2k + 1
We know that (k-1)^2>=0.
thus k^2>=2k-1
2^k + 2k + 1 = 2^k + 2k -1 + 2 <= 2^k + k^2 + 2 < 2^k + 2^k +2= 2^(k+1) + 2
Argh, i feel like im almost there. any help?