D since the other options increase at a constant rate. For A, each increase in x is +4. For B, each increase in x is +1. For C, each increase is 13
Angle bisector would be the answer
Let

In order to prove this by induction, we first need to prove the base case, i.e. prove that P(1) is true:

So, the base case is ok. Now, we need to assume
and prove
.
states that

Since we're assuming
, we can substitute the sum of the first n terms with their expression:

Which terminates the proof, since we showed that

as required