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#