Question

What is the 9th term of the geometric sequence 4, -20, 100, …?

-312,500
-12,500
62,500
1,562,500

Answer 1

\[a _{n}=a _{1}r ^{n-1}\]

Answer 2

where n=9, a1=4 and I'll let you work out the common ratio r

Answer 3

How do you find the common ratio?

Answer 4

just divide the second term by the first term or 3rd by the 2nd

Answer 5

thats the common ratio between terms

Answer 6

Its it 5?

Answer 7

Is the common ratio a 5?

Answer 8

No it's -20/4 = -5

Answer 9

now just plug the values into the equation