Let

where we assume |r| < 1. Multiplying on both sides by r gives

and subtracting this from
gives

As n → ∞, the exponential term will converge to 0, and the partial sums
will converge to

Now, we're given


We must have |r| < 1 since both sums converge, so


Solving for r by substitution, we have


Recalling the difference of squares identity, we have

We've already confirmed r ≠ 1, so we can simplify this to

It follows that

and so the sum we want is

which doesn't appear to be either of the given answer choices. Are you sure there isn't a typo somewhere?
Here is the answer Buddy
213.23
Answer:
there is only one easy way to sole this
using quadratic equation

Step-by-step explanation:
a=6 b=5 c=-6
and by applying it to the equation you will get
x=0.66 and x=-1.5
Answer:
Step-by-step explanation:
the expression for the perimeter would be
2(x) + 2(2x+7)
which can be simplified to 2x+4x+14
which equals 6x+14
Answer:
x - 17
Step-by-step explanation:
hope that helps