How do you find the sum of the infinite geometric series 4-1+1/4-1/16+...?

Dec 13, 2015

Infinite Sum $= \frac{{a}_{1}}{1 - r}$

Explanation:

For this problem ...

${a}_{1} = 4$
$r = - \frac{1}{4}$

Now, simply plug into the formula ...

Infinite Sum $= \frac{{a}_{1}}{1 - r} = \frac{4}{1 - \left(- \frac{1}{4}\right)} = \frac{16}{5} = 3.2$

hope that helped