Question

1. Is the sequence geometric? If so, identify the common ratio.

6, 12, 24, 48, ...

yes; 2
yes, –2
yes; 4
no

2.What is the fifth term of the geometric sequence?

5, 15, 45, ...

1,215
1,875
405
3,645

Answer 1

1. yes; 2

2. 405

3. an = -4 * (-2) ^n-1; -64

4. Triangle 4

5. 150

6. f(x) = 1/2 * 8 ^ x -1

Answer 2

1) yes;2 6*2=12 12*2=24 24*2=48
2)Next Term (or nth term) = ar^n-1

a = first term, i.e. 5
r = common ratio i.e. 3 (as 15/5=3 and 45/15=3
n = ..
as you already have 1st , 2nd and 3rd terms
substituting now
T4= ar^n-1
= 5*3^4-1
= 5*3^3
= 5*27
T4 = 135
T5= ar^n-1
= 5*3^5-1
= 5*3^4
= 5*81
T5 = 405