What is the next term in the geometric sequence -4,-12, 36 ?

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Answer 1 · 2018-06-05T11:17:39

$108$ $108$ if the initial sequence is corrected to $-4,12,-36,...$

Lets check the terms...

$(-12)/-4=3$

$36/(-12)=-3$ !!!!

There is not a comon ratio. the sequence must be

$-4, 12, -36,....$

In that case $r=-3$ and first term $-4$ , and then the next term is

$a_4=-36·(-3)=108$

so the general term is

$a_n=a_1r^(n-1)=-4·(-3)^(n-1)$