8, -2, -1/2,-1/8

(a)  

4, 8, 16, 32, ...

(a)  

1, -5, 25, -125, ...

(a)  

4, 3, 9/4, 27/16, ...

(a)  

64, -16, 4, -1, ...

(a)  

(a)  

 $\frac{1}{x}$   $\frac{1}{x},\ \frac{1}{x^2},\frac{1}{x^3},\ \frac{1}{x^4},\ ...$  

(a)  

  $\frac{5m}{2},\ \frac{25m}{4},\ \frac{125m}{8},\ ...$ 

(a)  

 $3x^3,\ -6x^5,\ 12x^7,\ ...$  

(a)