Posted by **Jon** on Tuesday, March 4, 2008 at 12:18pm.

Find a1 in a geometric series for which Sn=189,r=1/2,and an=3.

Sn=a1(1-r^n)/1-r

189=a1(1-1/2^3)/1-1/2

189=a1(-.5)/.5

189/-.25

a1=-756

## Answer this Question

## Related Questions

- Math - Whars 189.80. Times 6.25% less 33 1/3 % Is it 189.80 + 11.86 = 201.66 - ...
- math. HOW DO I CONVERT A DECIMAL TO A FRACTION - how do i convert a decimal to ...
- Algebra 2 - 5+(-5/2)+(5/4) Sn=189 Find n for the given sum if the geometric ...
- Geometry repost - "yes, except 20/36 / 21/x x= 189/5 = 37.8 seems to have a typo...
- MATH - 1.32 + 0.987 + 3.07 = a-4.089 b-5.089 c-5.189 d-6.189 e-13.972 answer-5....
- chem - Consider a Carnot engine operating between the temperatures of 300. K and...
- chemistry - Temp - 650 Pressure - 760mm Hg mass - 0.927g volume - ? I need to ...
- college physics - A 0.384 kg puck, initially at rest on a horizon- tal, ...
- math - I am doing something wrong when I work this question. Can someone show me...
- Statistics help Please - The table below reports birth weight and whether the ...