The sum of an infinite geometric series is 125, and the value of r is 0.4. How do you find the first three terms of the series?

Question

The sum of an infinite geometric series is 125, and the value of r is 0.4. How do you find the first three terms of the series?

1 Answer

Impact of this question

2770 views around the world

You can reuse this answer
Creative Commons License

Answer 1 · 2016-11-13T20:04:01

The first three terms are $75, 30, 12$ $75, 30, 12$ .

Explanation:

The formula for sum of an infinite, convergent geometric series is $s_{\infty} = \frac{a}{1 - r}$ $s_oo = a/(1- r)$ , where $s_{\infty}$ $s_oo$ is the sum, $a$ $a$ is the first term of the series and $r$ $r$ is the common ratio.

Hence,

$125 = \frac{a}{1 - 0.4}$ $125 = a/(1 - 0.4)$

$125 \times 0.6 = a$ $125 xx 0.6 = a$

$a = 75$ $a = 75$

We know that $r = 0.4$ $r = 0.4$ , so:

$t_{2} = 75 \times 0.4 = 30$ $t_2 = 75 xx 0.4 = 30$

$t_{3} = 30 \times 0.4 = 12$ $t_3 = 30 xx 0.4 = 12$

Hopefully this helps!

Science

Math

Humanities

... and beyond

The sum of an infinite geometric series is 125, and the value of r is 0.4. How do you find the first three terms of the series?

1 Answer

Explanation:

Related questions

Impact of this question