<u>Understanding:</u>
The sum of a geometric series is, 
, with a being the start point and r is the common ratio. We can also use the following formula to make life easier 
, a is your start point, r is the common ratio, and n is the number of terms, which in our case is S7.
<u>Solution:</u>
Our start point is 1, 
,
The common ratio is 5, 
,
And finally, the number of terms is 7, 
.
The answer is [A] 19531.
The sum of the given polynomial is 5x²- 5x +9
<h3>Sum of polynomial</h3>
Polynomials are expressions with a degree of 3 and above. Given the equation shown;
(3x + 4) + ((5x²-1) + (2x + 6))
Expand
(3x + 4) + ((5x²-1) + (2x + 6))
3x + 4 + 5x²-1 + 2x + 6
Collect the like terms
5x² + 5x + 4 - 1 + 6
5x²- 5x +9
Hence the sum of the given polynomial is 5x²- 5x +9
Learn more on polynomial here; brainly.com/question/2833285
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F(13) means x equals 13.
Replace x in the equation with 13 and solve:
-13 + 3 = -10
F(13) = -10
