Question

mathematical induction

How the 3(k-1) - 1 came in third step???????? ​

Answer 1

I think it is written $3^{(k+1)-1}$.

Just take screenshot and zoom in, you will see it.

Answer 2

hey mate hope it helps you..

The last term can be written as 3^k

The second last will be 3^k-1

3^k can also be written as 3^(k+1)-1

3^(k+1-1) = 3^k+0 = 3^k