Hi it is 7n I hope I was right
I think the answer is -280y^2+40y
Work shown above! Answer is x = 4 and x = 10
Basically you get all the numbers to one side which makes it a quadratic formula. Then you solve for x by factoring and that's it!
ANSWER
EXPLANATION
The given infinite series is
The sum to infinity of this series is given by the formula,
where the first term of this infinite geometric series is
and the common ratio is
We substitute these values to obtain,
We simplify the denominator to get,
This simplifies to
The cost is the number of videos (V) times the cost of a video, plus the monthly fee.
C=2.25V+5