Need help with the following induction proving?

[joe12]

1+3+3^2+....3^n-1=1/2(3^n -1)..how to prove this induction???

 

[pka]

1+3+3^2+....3^n-1=1/2(3^n -1)..how to prove this induction???

What is the base case? Is it true?

 

[HallsofIvy]

1+3+3^2+....3^n-1=1/2(3^n -1)..how to prove this induction???

Do you mean 3^(n- 1) or (3^n)-1?
Do you mean (1/2)((3^n)- 1) or (1/2)(3^(n-1))?

 

[stapel]

1+3+3^2+....3^n-1=1/2(3^n -1)..how to prove this induction?

To learn how to do induction proofs, try here.