Question

Use mathematical induction to prove the statement is true for all positive integers n.

6 + 12 + 18 + ... + 6n = 3n(n + 1)

Here's what I have so far:

Answer 1

6+12+18+...6(1)=3(1)((1)+1)
6=3(2)
6=6
true for n=1

assume that n=k

Answer 2

do i prove k+1?