Question

find a10 for the geometric sequence An = 3(4)n-1

A: 262,144
B: 786,432
C: 1,048,579
D: 3,145,728
really need help really lost!!! :(

Answer 1

Are you sure it looks like this? I can't tell if i'm suppose to subtract 1 first or multiply.

Answer 2

yes you suppose to multiply

Answer 3

\[a _{n}=a _{1}\times r ^{n-1}\]
That's the formula for geometric sequence.

Answer 4

B

Answer 5

Ah ok I got it you wrote it wrong. It's suppose to be An=3 x (4)^n-1
Plug and chug
3 x (4)^9= a(10)
Do 4^9 first and it equals = 262144
Now multiply that by 3 and it's 786432

Answer 6

thnkz so much I was lost but now I got the solving down thnkz CP & WORDGEEK :)