Question

Find the indicate term for each geometric series described

Answer 1

\[Find : a _{1}\]\[s _{n}=33\]\[a _{n}=48\]\[r=-2\]

Answer 2

the key a1 =3

Answer 3

u sure u got question right?

Answer 4

how many gs\s are there?

Answer 5

yes,I sure

Answer 6

how many geometric series are we talking about?

Answer 7

that all I get from question

Answer 8

I don't know

Answer 9

the formular:\[s _{n}=\frac{a _{1}(1-r^n)}{1-r}\]

Answer 10

ok i made a mistake - i used n = 2 - sorry

Answer 11

try again

Answer 12

I can't do it , because without n I can't solve

Answer 13

be back

Answer 14

it geting late I go sleepp ,if u fid answer , fust write it , I will check back tomorrow ,TY

Answer 15

33 = a1(1 - (-2)^n) / 1-(-2)
33 = a1(1 - (-2)^n) / 3............(1)
also 48 = a1*(-2)^(n- 1)...........(2)
equations (1) and (2) need to be solved simultaneously

Answer 16

ok

Answer 17

from (1)
99 = a1 (1 - (-2)^2)........(3)
from (2)
48 = a1 ((-2)^n * (-2)^-1) = a1 ((-2)^2 * -1/2))
48 = (-a1/2)(-2)^n
(-2)^n = -96/a1
plug (-2)^n = -96/a1 into (3)
99 = a1 (1 +96/a1)
99 = a1 + 96
a1 = 99-96 = 3