Question

HElp

The first term in an arithmetic sequence is 5. The third term in the sequence is -1. The tenth term in the sequence is -22.
Which of the following functions can be used to find the nth term of the arithmetic sequence?
A.f(n) = -n
B.f(n) = n + 4
C.f(n) = -3n + 8
D.f(n) = 0.5(n+5) + 2

Answer 1

C.(n) = -3n + 8

Explanation:

let the difference between the first term and second term be x

we know,

first term(a)=5

third term(c)=-1

now,

5+x=-1-x

or,

2x=-6

or,

x=-3

so the difference between the terms is -3

Again,

nth term = a+(n-1)x

=5+(n-1)-3

= 5-3n+3

=-3n+8