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8 votes
Find the 15th term of the geometric sequence 2,−8,32,...

User Bruce Lee
by
5.1k points

2 Answers

4 votes

Answer: first term (a)= 2

second term (b) = -8

common ratio (r) = -8/2 = -4

15th term = ar^ (n-1)

= 2* (-4)^ 14 =536870912

Explanation:

User Mwfearnley
by
6.0k points
6 votes

Answer:

536,870,912

Explanation:

the formula for geometric sequences is:

aₙ = a₁·
r^(n-1)

where aₙ is, in this case the 15th term

r = common ratio which, in this case, is -4

a₁ = first value in the sequence

so:

a₁₅= 2(-4)^14

= 2(268,435,456)

= 536,870,912