Use the Formula for the General Term of a Geometric SequenceUse the formula for the general term (the nth term)of a geometric sequence to find the indicated term of the
sequence with the given first term, $$\mathbf { a } _ { 1 }$$ , and common ratio, r.
-Find a9 when $a _ { 1 } = - 2 , r = 2$.
A) $- 512$
B) $- 1024$
C) $- 508$
D) 14

Question

Quizplus · Accepted Answer

The formula for the nth term of a geometric sequence is $a_n = a_1 \cdot r^{(n-1)}$. Plugging in the given values, $a_9 = -2 \cdot 2^{(9-1)} = -2 \cdot 2^8 = -2 \cdot 256 = -512$.

Use the Formula for the General Term of a Geometric a1\mathbf { a } _ { 1 }a1​

Use the Formula for the General Term of a Geometric $\mathbf { a } _ { 1 }$