Posted by curious student on .
write the following in a sigma notation
3/32+3/16+3/8+...+12288
so far ive gotten that a=3/32 and r=2/1
can you please help me further

math 
Reiny,
sum = [sigma] 3/2^(6i), i from 1 to 18

math 
curious student,
what does "i" stand for?

math 
Reiny,
In sigma notation we traditionally use i or n as the index of the notation.
You had asked for the expression in "sigma notation"
What you started doing is attempting to add up the values using a geometric series.
What you started is correct, but that was not asked for.
If you want the actual sum, you will first have to find how many terms there are, that is, what term number is 12288
the use the formula
S_{n} = a(r^n  1)/(r1) 
math 
curious student,
thank you muchly!