Question

PLEASE HELP!!!!!! 20 POINTS!!!!!

Answer 1

Answer:

-18.703

Step-by-step explanation:

a₁=-28(-1/2)¹⁻¹

r=-1/2

a₁=-28

r=-1/2

S₉=a₁$\frac{1-r^{9} }{1-r}$

S₉=-28$\frac{1-(\frac{1}{2})^{9} }{1-(\frac{1}{2}) }$

S₉=$-\frac{1197}{64}$

S₉=-18$\frac{45}{64}$   S₉=-18.703125