A1 or just a as it is in the equations is just the initial term of the sequence. In this case a1=1
r is the common ratio which is that constant ratio found by dividing any term by the term preceding it...
In this case r=3/1=9/3=27/9=etc=3
So a1=1 and r=3, C. is your answer.
12.....because there are 4 quarters in $1
(0,0) and (6,0)
First we subtract 18x from both sides
3x²-18x=0
Factor out a 3x
3x(x-6)=0
This means that x is either 0 or 6
