find the explicit formula.

Question

1. 0.5, -1, 2, -4 ...

2. 5, -5/3, 5/9, -5/27 ...

3. 1.25, 5, 20, 80 ....

4. -4, -24, -144, -864 ...

5. 4, 12, 36, 108 ...

6. 3, -15, 75, -375 ...

7. 2, 4, 8, 16 ...

8. 3/2, 3/4, 3/8, 3/16 ...

9. -1, -6, -36, -216 ...

10. 3, 12, 48, 192 ...

Answer 1

1. geometric series
a r^(n-1)
a = .5, r = -2
.5 *(-2)^(n-1)

2. same deal
5 *(-1/3)^n-1

and on and on .....