What is the explicit rule for this geometric sequence? a1=−15;an=15⋅an−1

an=−15⋅15n−1

an=−15(15)n−1

an=15(−15)n−1

an=15⋅(−15)n−1

I'm not sure if I'm 100% correct but I think it is C

Step-by-step explanation:

an=1/5⋅(−15)n−1

Step-by-step explanation:

I think the problem is a1=−15;an=1/5⋅an−1 and not a1=−15;an=15⋅an−1

I took the test :)

let x and 400 - x be the two numbers.  

==> 0.80x + 0.85(400 - x) = 400 - 68 from the statement of the problem.  

< ==> 0.80x + 0.85(400 - x) = 400 - 68  

==> 340 - 0.05x = 332  

< ==> -0.05x = -8 ==> x = 160, the first number ==> 400 - x = 240, the second number.