find the sum to the required number of terms for the geometric series
2-1+1/2 -1/4+... to 6 terms

just want to check if i got the answer right. using the formula s=b1*(1-q^n)/(1-q) , i got 21/16
is that right?

Question

find the sum to the required number of terms for the geometric series
2-1+1/2 -1/4+... to 6 terms 

just want to check if i got the answer right. using the formula s=b1*(1-q^n)/(1-q) , i got 21/16 
is that right?

parthkohli · Answer

$$1 + 1/2 - 1/4 + 1/8 - 1/16 \ = 1+1/4 + 1/8 - 1/16\ = 1 + 3/8 - 1/16\ = 1 + 5/8$$

parthkohli · Answer

So you're correct!

parthkohli · Answer

When I don't have a paper, I just add those up. Haha

anonymous · Answer

but 1+5/8 is 13/8

anonymous · Answer

13/8 = 1.625 
and 21/16=1.31

goformit100 · Answer

Where is the lamp @AravindG

parthkohli · Answer

grr, I meant $1 + \dfrac{5}{16}$

anonymous · Answer

ohh lol ok that makes sense

goformit100 · Answer

grr nice peculiure sound you make

goformit100 · Answer

@ParthKohli it was for you baby