Determine whether the geometric series is convergent or divergent. If it is convergent, find its sum. 7 + 6 + 36/7 + 216/49 + ...
If it is convergent, find its sum.

- L < 1, so by series ratio test, It is convergent

- sum of the convergent series is 49

Step-by-step explanation:

Given the data in the question;

series = 7 + 6 + 36/7 + 216/49 + .........

⇒ 7 + 7 × 6/7 + 7 × 36/49 + 7 × 216/343 +........

⇒ 7 + 7 × 6/7 + 7 × 6²/7² + 7 × 6³/7³ .....

⇒ 7( 1 + 6/7 + 6²/7² + 6³/7³ + ..... )

⇒ 7 ∞∑_ 6/7

⇒ ∞∑_ ( / )

So, L =  

=

=

= 6 /7

L < 1

so by series ratio test,

It is convergent

So we find the sun;

Sum of  infinite geometric series is;

⇒ a / (1-r)

here, a = first number and r = common ratio

∑ = 7( 1 + 6/7 + 6²/7² + 6³/7³ + ..... )

a = 1 and r = 6/7

so

∑ = 7( )

= 7( )

= 7( )

= 7( 7 )

= 49

Therefore, sum of the convergent series is 49