Question

How do I find the 16th term of a geometric sequence where a{subscript(1)} = 4 and a{subscript(8)} = -8,748.

Answer 1

\[a _{1}=4\]and\[a _{8}=-8,748\]

Answer 2

since you know a1, and the general formula for a geometric sequence is:\[a_n=a_1~r^{n-1}\]

you can determine r readily

Answer 3

\[4\times r ^{7}= -8748\]

Answer 4

\[\sqrt[7]{-2187} = -3 = r \]

Answer 5

\[ar ^{15}= 4 \times (-3)^{15}= -57395628\]

Answer 6

Thanks!