High School Pre-Cal

Question

What is the sum of the following infinite series?

 

7-7 + 7 - 7

   --    --   -- +

   2    4    8

        _
A. 4.6

        _

B. 4.7

        _

C. 4.8

 

D. ∞

Answer 1

S = a_{1 / (1 - r)}

S = 7 / (1 + 0.5)

S = 7 / 1.5

S = 14/3

Answer 2

I presume you mean

7[1 - (1/2) + (1/4) - (18) .... = 7/[1+(1/2)] = 14/3 = 4.666666 which rounds off to 4.7

 

The is is an infinite geometric series with the ration of successive terms = -/2.