Answer:
Step-by-step explanation:
The general form for a geometric sequence is:
a
n
=
a
1
⋅
r
n
−
1
With this, you can write a system of equations:
a
2
=
a
1
⋅
r
2
−
1
a
5
=
a
1
⋅
r
5
−
1
2
=
a
1
⋅
r
1
0.25
=
a
1
⋅
r
4
r
4
r
1
=
0.25
2
r
3
=
0.125
r
=
0.5
Now, find the first term.
a
2
=
a
1
⋅
0.5
1
2
=
a
1
⋅
0.5
a
1
=
4
Using the formula stated above, we get:
a
n
=
4
⋅
0.5
n
−
1
