Thursday

December 18, 2014

December 18, 2014

Posted by **purple1** on Saturday, March 20, 2010 at 8:14pm.

9-3+1-1/3+1/9...

1/2+1+2+4...

- math -
**Reiny**, Saturday, March 20, 2010 at 8:40pmS

_{∞}= a/(1/r) where │r│ < 1

in the first,

a = 9, r = -1/3

so sum = 9/(1 - (-1/3)) = 6.75 or 27/4

For the second one, there is no sum, since the series diverges.

notice r = 2, so it does not satisfy the condition for the formula.

- math -
**purple1**, Saturday, March 20, 2010 at 8:44pmThank you.

- typo - math -
**Reiny**, Saturday, March 20, 2010 at 8:49pmI just notice a typo in my formula, should of course be

a/(1-r) where │r│ < 1

I did use it correctly in the calculations

**Answer this Question**

**Related Questions**

Calculus - The problem I have is a summation from 1 to infinity for (-1)^n/n. I ...

Math 12th grade - Find the sum of each infinite series, or state that the sum ...

algebra(check) - 1)Find a1 in a geometric series for which Sn=300,r=-3,and n=4 a...

sum geometric series - what is the sum of geometric infinite series 3/2+ 9/16+ ...

math - 1)Find a1 in a geometric series for which Sn=300,r=-3,and n=4 A)15 B)15/2...

algebra - 1)Find a1 in a geometric series for which Sn=300,r=-3,and n=4 a.15 b....

algebra - 1)Find a1 in a geometric series for which Sn=300,r=-3,and n=4 a.15 b....

algebra - 1)Find a1 in a geometric series for which Sn=300,r=-3,and n=4 a.15 b....

math(need 2nd opinion) - 1)Find a1 in a geometric series for which Sn=300,r=-3,...

calculus - Consider the infinite series of the form: (+/-)3(+/-)1(+/-)(1/3...