# Math Help - Formula for the sequence

1. ## Formula for the sequence

I know the difference is (-2/3), but I can't seem to figure out the formula.

Thanks,

2. ## Re: Formula for the sequence

The ratio is (-2/3)

the nth term is given by $(-8)* \cdot (-2/3)^{n-1}$

3. ## Re: Formula for the sequence

Originally Posted by l flipboi l
Hello, can someone please help me find the formula for the sequence? I know the difference is (-2/3), but I can't seem to figure out the formula.
Try $a_n=\frac{(-2)^{n+3}}{3^{n}},~n=0,1,\cdots$

4. ## Re: Formula for the sequence

Hi,
The nth term is given by Tn=a+(n-1)d
=-8+(n-1)(-2/3)
=-11/3(2+n).

5. ## Re: Formula for the sequence

Originally Posted by Plato
Try $a_n=\frac{(-2)^{n+3}}{3^{n}},~n=0,1,\cdots$
thx, but n is suppose to start at 1.

so the first term a1 = -8.

thanks!

7. ## Re: Formula for the sequence

Originally Posted by l flipboi l
thx, but n is suppose to start at 1.

so the first term a1 = -8.
That's an easy fix... (!)
Replace "n" with "n - 1" in P's solution.

8. ## Re: Formula for the sequence

Originally Posted by deepashree
Hi,
The nth term is given by Tn=a+(n-1)d
=-8+(n-1)(-2/3)
=-11/3(2+n).
fyi, the sequence is geometric, not arithmetic.

9. ## Re: Formula for the sequence

Thanks, everyone!