Okay, first, given the equation, we need to find out what the radius of the circle is. Let us state the general equation of a circle:

Where

is the centre of the circle. In this case, we don't need to know the centre. Just the radius.
Let us start by converting the equation into standard for, which I typed above. Divide both sides by 81.

Great! We now know the radius of the circle. It is

because it is the bottom fraction. Now we know that the radius is 9.
So now lets input this into the area of circle formula:
Now we insert our radius.
You can convert that into a decimal if you wish.
Hope this helped!
~Cam943, Moderator
Answer:
23-5= 18
Step-by-step explanation:
Answer:
y=4
Step-by-step explanation:
You can ignore the 3 and 6 because this has no y value change(rise over run)
This is a straight horizontal line so the equation is y=4.
Slope=0
The sequence is geometric, so

for some constant r. From this rule, it follows that

and we can determine the first term to be

Now, by substitution we have

and so on down to (D)

(notice how the exponent on r and the subscript on a add up to n)