Find the 25th term from the following

Question

0, 1, 2, 3, 4, .........

Answer 1

This is how you're problem in the table:

n = 1. 2. 3. 4. 5. ... n

a_n =0. 1. 2. 3. 6.... n -1

You will notice the if n = 1, a_n =0

if n = 2, a_n =1

if n = 3, a_n =2 and so on... This is what you called an arithmetic sequence.

Also you'll see that n is always one unit ahead of a_n, Therefore we can put the equation of the sequence as:

a_n = n -1

So if you are looking for the 25th term, you are looking for a₂₅.

a₂₅ = 25 - 1 = 24.