If the game only has 20 levels, explain how to find the value of the series for the coins and the points. Use complete sentences and arrive at final values.

I already did the coins one by myself im having trouble with this part because i am plugging my data into a1–a1(r)^(n) / 1- r. My formula (3-3(3)^(3))/(1-3) for the third level.
Level Points
1 3
2 9
3 27

Question

If the game only has 20 levels, explain how to find the value of the series for the coins and the points. Use complete sentences and arrive at final values. 

I already did the coins one by myself im having trouble with this part because i am plugging my data into a1–a1(r)^(n) / 1- r. My formula (3-3(3)^(3))/(1-3) for the third level.
Level	Points
1	3 
2	9
3	27

anonymous · Answer

but i keep getting 39 instead of 27

anonymous · Answer

@texaschic101

anonymous · Answer

@primeralph

anonymous · Answer

chvmjay you any good witth this

anonymous · Answer

@phi I need your help

anonymous · Answer

fail im in chemistry

chmvijay · Answer

lol this is maths question just post it there :) u get a help soon @HelpMePlease?

phi · Answer

yes, you should post in math... but your formula gives the *sum* of the points for level=1 to 3

notice that 3+9+27= 39  which is what you are getting.

If you want the nth value, use  3^n  for n starting at 1
if you use that formula, you find the 3rd value is 3^3 = 27