How do you find $a_8$ for the geometric sequence $4, -12, 36,...$ ?

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Answer 1 · 2016-10-16T14:50:39

$a_8 = -8,748$

To find the value of a term in a GP, you need to know:

$a_1, r and n$

$a_1 = 4$

$r = (-12)/4 = -3$

for $a_8, n = 8$

$a_n = a_1 xx r^(n-1)" "larr$ the general term

$a_8 = 4 xx (-3)^7$

$a_8 = -8,748$

How do you find a_8a_8 for the geometric sequence 4, -12, 36,...4, -12, 36,...?