Question

Find the 91st term of the arithmetic sequence 28, 8, –12, ...

Anybody know the answer?

Answer 1

-1772

Explanation:

The nth term of an arithmetic sequence is expressed as;

Tn = a+(n-1)d

a is the first term

n is the number of terms

d is the common difference

From the sequence

a = 28

d = 8-28 = -12-8 = -20

n =91(since we are looking for the 91st term)

Substrate

T91 = 28+(91-1)(-20)

T91 = 28+90(-20)

T91 = 28-1800

T91 = -1772

Hence the 91st term is -1772