## jaylelile one year ago 8.Sebastian writes the recursive formula f(x+1) = 4f(x) to represent a geometric sequence whose second term is 12. Which explicit formula can be used to model the same sequence? f(x) = 12(4)x f(x) = 3(4)x − 1 f(x) = 4(12)x f(x) = 4(3)x − 1

1. misssunshinexxoxo

Which one do you believe it is?

2. jaylelile

I come up with different answers every time

3. anonymous

If f(2)=12 then f(2+1)=4(12) Now go to the general formula for a geometric sequence. $a _{n}=a _{1}*r ^{(n-1)}$ Since f(3)=48 and f(2)=12 or you can say $a _{3}=48$ and $a _{2}=12$ Since $r=\frac{ a _{n +1} }{ a _{n} }$then r= 48/12 or 4 Now find $a _{1}$ from the formula for n=3 $48=a _{1}*4^{(3-1)}$ So $a _{1}=3$ So it looks like $f(x)=3*4^{x-1}$