How to find a formula for the nth term?

Question

Common difference : 5
First term: 5

Common difference: -3
First term: 15

Common difference: 6
First term: -5

Answer 1

a_n = a₁ + (n-1)d

 

Example:

common difference 4

first term = 6

 

a_n = 6 + (n-1)4

Find 7th term

a₇ = 6 + (7-1)(4) = 6+24=30

 

Try yours now.  :-)