Find the 9th term of the geometric sequence –1, 3, –9, …

Evelyn Freeman

Evelyn Freeman

Answered question

2022-10-29

Find the 9th term of the geometric sequence –1, 3, –9, …

Answer & Explanation

Messiah Trevino

Messiah Trevino

Beginner2022-10-30Added 18 answers

a 2 a 1 = 3 - 1 = - 3
a 3 a 2 = - 9 3 = - 3
⇒ common ratio=r=−3 and a 1 = - 1
We know that:
a n = a 1 r n - 1
a 9 = ( - 1 ) ( - 3 ) 9 - 1 = ( - 1 ) ( - 3 ) 8 = ( - 1 ) 6561 = - 6561
a 9 = - 6561

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