The common ratio in a geometric sequence is 3/2, and the fifth term is 1. How do you find the first three terms?

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Answer 1 · 2016-05-22T06:28:39

#16/81#, #8/27#, #4/9#

The formula for finding the #n^"th"# ( #U_n#) term in a geometric sequence is

#U_n=U_1xxr^"n-1"#

where #r# is the common ratio.

#U_1 = ?#
#U_5 = 1#
#r = 3/2#

#U_5=U_1xx(3/2)^"5-1"#

#1=U_1xx(3/2)^"4"#

Rearrange

#1/(3/2)^"4"=U_1#

#U_1=1/(81/16)=16/81#

#U_2=16/81xx3/2=8/27#

#U_3=8/27xx3/2=4/9#