The equation could be used to calculate the sum of the geometric series is 
<h3>Sum of geometric sequence</h3>
Geometric sequence are sequence that increase expoentially. The formula for calculating the sum of an exponential sequence is expressed as:

where
- a is the first term
- n is the number of terms
- r is the common ratio
From the given sequence
a= 1/3
r = 2/9 * 3 = 2/3
Substitute into the formula

Hence the equation could be used to calculate the sum of the geometric series is 
Learn more on geometric series here; brainly.com/question/24643676
It it is the first choice i mentioned then B is the answer.
Answer:
C. green is not a function, red is a function
Step-by-step explanation:
A curve does not describe a functional relationship if a vertical line crosses it in more than one place. Clearly the y-axis crosses the green curve in 2 places, so it is NOT a function.
There is a very steep section at x=10 on the red curve. It we assume it is simply "very steep" and not "vertical", then the red curve IS a function. If you assume that short section is vertical, then the red curve is not a function, either. My choice is to go with "very steep," not "vertical."
My conclusion is that green is not a function; red is a function.
Answer:
(9, -2)
Step-by-step explanation:


(9, -2)
-9<0
Because 9 is negative, it's value is less than 0