Here we're discussing the "nth partial sum of a geom series."
1 - r^n
The formula for that is s(n) = a(1) ---------------
1-r
We can subst. the given values and see where that takes us:
1 - (-2)^6 1 - 64
105 = a(1)*---------------- = ----------*a(1) = -21*a(1)
1-(-2) 3
105
Solving this for a(1): a(1) = --------- = -5 (answer)
-21
Find the area of each shape and add.Let's start with the first semi-circle(half-circle)
If the area of a circle is πr² , then the area of a semi-circle is 1/2πr² where is 22/7 or 3.14, and r is the radius which is 1.8 meters
A=1/2πr²
A=1/2*22/7*1.8*1.8
A=5.09 m²(rounded to nearest hundredth)
Since the semi-circles are two and have the same radius, multiply the area of the first one by two or go through the same process again.
So 5.09 *2=10.18meters square is the area of the two semi-circles
Now, let's find the area of a rectangle which is length times width, where length is 6 meters and width is (1.8+1.8, because 1.8 is half the width)=3.6 meters
A=l*w
A=6*3.6
A=21.6meters square
Therefore the area of the shape is 10.18m²+21.6m²=219.888m²
So this equation is in exponential equation format, which is 
, with a = initial value (aka y-intercept) and b = growth/decay.
Looking at our equation, since 1 is in the a placeholder, this means that the <em>y-intercept is (0,1)</em>. Looking at our four graphs, the only graph that has (0,1) as the y-intercept is the third graph. Therefore, <u>the correct answer is the third graph.</u>
