I need to show that the right side equals the left side but I am having a little trouble simplifying.

k(2k+1) +(4(k+1)-1) = (k+1)(2(k+1)+1)

k^2+2k+3 For the right side?

No, for right side:

(k+1)(2(k+1)+1) = (k+1)(2k+2+1) = (k+1)(2k+3) = 2k^2 + 5k + 3