Question

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

an=4(40)n−1
𝑎
𝑛
=
4
(
40
)
𝑛
−
1
a subscript n baseline equals 4 left parenthesis 40 right parenthesis superscript n minus 1 baseline

an=40(120)n−1
𝑎
𝑛
=
40
(
120
)
𝑛
−
1
a subscript n baseline equals 40 left parenthesis 120 right parenthesis superscript n minus 1 baseline

an=40+4(n−1)
𝑎
𝑛
=
40
+
4
(
𝑛
−
1
)
a subscript n baseline equals 40 plus 4 left parenthesis n minus 1 right parenthesis

an=40(4)n−1

Answer 1

The sequence has first term 40 and common ratio 160/40 = 4, so the formula is
a_n = 40(4)^{n-1}.