Question

Which exponential function can be used to show the geometric sequence 40, 160, 640, . . . ?(1 point)
Responses

an=40(120)n−1

a subscript n baseline equals 40 left parenthesis 120 right parenthesis superscript n minus 1 baseline

an=4(40)n−1

a subscript n baseline equals 4 left parenthesis 40 right parenthesis superscript n minus 1 baseline

an=40+4(n−1)

a subscript n baseline equals 40 plus 4 left parenthesis n minus 1 right parenthesis

an=40(4)n−1

a subscript n baseline equals 40 left parenthesis 4 right parenthesis superscript n minus 1 baseline

Answer 1

an = 40(4)^(n−1)

Reason: each term is multiplied by 4, so the common ratio is 4. Check: n=1 → 40, n=2 → 40·4 = 160, n=3 → 40·4^2 = 640.