I am looking at mathamatical induction and seem to be stuck on why the answer to a factoring step is correct.
r(r+1)+2(r+1) factored by r+1 gives (r+1)(r+2)
2(r+1) factored by r+1 to give (r+2) is clear but I cannot fathom r(r+1) factored by r+1 gives r+1.
Here is the link to the page on induction and is below line 1
Mathematical induction - Topics in precalculus
This is my first post here so please be gentle.