Question

Find the 16th term of the series 7+2-3-8-13-•••••••••

Answer 1

Common difference is -5.
Thus, this will be an arithmetic series.

Sum is given by:

`a_n = (n)/(2)[2a_1 + (n - 1)d]`

`a_(16) = (16)/(2)[2(7) + (16 - 1)(-5)]`

`= 8[14 + (15)(-5)]`

`= 8[14 - 75]`

`= 8(-61)`

`= -488`