Question

An arithmetic sequence is shown below. −7,−3,1,5,9,... Which represents an explicit formula for this sequence. A f(n) = -7 +4 (n-1) B f(n) = -4 +7 (n-1) C f(n) = -4 +7 (n-1) D f(n) = -11 (n-1)

Answer 1

A. f(n) = -7 +4 (n-1)

Explanation:

`a_1=-7\,,\ a_2=-3\,,\ a_3=1\,,\ a_4=5\,,\ a_5=9...\implies d=4`

{-3-(-7)=4 and 1-(-3)=4 and 5-1=4 and 9-5=4}

An arithmetic sequence is:
`a_n=a_1+(n-1)d`

`a_1=-7\quad and\quad d=4`

`a_n=-7+(n-1)\cdot4`

So:

`f(n)=-7+4(n-1)`

Answer 2

The answer of this question would be A:)