Geometric sequence 4

It is given geometric sequence a3 = 7 and a12 = 3. Calculate s23 (= sum of the first 23 members of the sequence).

Correct answer:

s23 =  83.26

Step-by-step explanation:

a3=a1q31=7 a12=a1q121=3  3/7=q123=q9 q=3/79=0.9102  a10.910231=7 a1=7/0.910231=8.4503  s23=a1q231q1=8.45030.91022310.91021=83.26



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