Use the Formula for the General Term of a Geometric Sequence
-Find a9 when $a _ { 1 } = 4 , r = 2$.
A) 1024
B) 2048
C) 1028
D) 20

Name: Use the Formula for the General Term of a Geometric Sequence -Find a9 when $a _ { 1 } = 4 , r = 2$. A) 1024 B) 2048 C) 1028 D) 20
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Question

Quizplus · Accepted Answer

The formula for the nth term of a geometric sequence is $a_n = a_1 \cdot r^{(n-1)}$. For $a_9$, $n = 9$, $a_1 = 4$, and $r = 2$, so $a_9 = 4 \cdot 2^{(9-1)} = 4 \cdot 2^8 = 4 \cdot 256 = 1024$.

Use the Formula for the General Term of a Geometric a1=4,r=2a _ { 1 } = 4 , r = 2a1​=4,r=2

Use the Formula for the General Term of a Geometric $a _ { 1 } = 4 , r = 2$