Question

What is the 12th term of the sequence 15, 11, 7, …?

15 - 11 = 4
So there is a common difference of 4
I know I can subtract 4, 12 times to find the twelfth term but is there a faster way?

Answer 1

if the sequence starts with 0 the 12th term is -44,as it starts with 15 we must add 15 to -44 which gives -29

Answer 2

this is a much faster way

Answer 3

\[a _{n}=a _{1}+(n-1)d\]

Answer 4

\[a _{n}\] = last term


\[a _{1} =\] first term

n = number of terms

d = difference

Answer 5

Thank you :)