Question

Prove 3+4+5+...+(n+2) = [n(n+5)]/2 for n>4
Do the first step in a proof by induction.

Answer 1

You must have a typo

in 3+4+5+ ... + (n+2)

the general term does not match your first three numbers

Answer 2

I'm not sure. It was on my math test. I typed it out exactly like it said on the test.