Use 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, a1, and common ratio, r.
-Find a12 when a1 = -4, r = 2.
A) 18
B) -8,192
C) -16,384
D) -8,188

Question

Quizplus · Accepted Answer

The nth term of a geometric sequence is given by $a_n = a_1 \cdot r^{(n-1)}$. For $a_{12}$, $a_1 = -4$, $r = 2$, and $n = 12$, so $a_{12} = -4 \cdot 2^{(12-1)} = -4 \cdot 2^{11} = -4 \cdot 2048 = -8,192$.

Use the Formula for the General Term (The Nth Term)