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!!! :(

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!!! :(

anonymous · Answer

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

anonymous · Answer

yes you suppose to multiply

anonymous · Answer

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

cp9454 · Answer

B

anonymous · Answer

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

anonymous · Answer

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