Question

What is the 48th term of the arithmetic sequence with this explicit formula?

an=-11 + (n - 1)(-3)

Answer 1

-149

Explanation:

`a_(n)` =-11 + (n - 1)(-3)

by observation

when n = 0,
`a_(0)` = 1st term

when n = 1,
`a_(1)` = 2nd term

.....

when n = x,
`a_(x)` = (x+1)th term

hence if we want to find the 48th term, n = 48 - 1 = 47

when n = 47,
`a_(47)` = 48th term

= -11 + (47-1)(-3)

= -11 + 46(-3)

= - 11 - 138

= -149