Demo

Linear Sequences

Finding the nth term

Find the expression for the nth term of

7 11 15 19 23 ...

7 11 15 19 23 ....

It goes up by 4 each time

• so it must have a 4n in the formula

• but when n=1, 4n = 4 and we need 7

• so there must also be a +3

• Answer: 4n + 3

• Check: if n=2, 4n+ 3 = 11 [hoorah]