Question 1170436
the common ratio is 3 since between the 3rd and 5th is a 9-fold increase
a1 is unknown
a2=3a1
a3=9a1
a5=81a1
a6=243a1
a7=729a1
the last two add to 1944=972a1
so a1=2, and r=3
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sum of first 10 terms is 2(1-3^10)/-2=59048
sum of first four terms is 2(1-3^4)/-2=80
the sum of the 4th-10th terms inclusive is 58968
the series is 2/6/18/54/162/486/1458/4374/13122/39366