SOLUTION: Tn=3r^n-1,where r>0 Is the nth term of a geometric sequence. If the third term is 48 determine r

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Question 1127086: Tn=3r^n-1,where r>0 Is the nth term of a geometric sequence. If the third term is 48 determine r
Found 2 solutions by ikleyn, MathLover1:
Answer by ikleyn(52787) About Me  (Show Source):
You can put this solution on YOUR website!
.
T%5B3%5D = 3%2Ar%5E2 = 48  ====>


r%5E2 = 48%2F3 = 16  ====>  r = sqrt%2816%29 = +/- 4.


Since r should be positive, according to the condition, it implies that r = 4.



Answer.  r,  or the common ratio, is equal to  4.


Answer by MathLover1(20850) About Me  (Show Source):
You can put this solution on YOUR website!

T%5Bn%5D=3r%5E%28n-1%29,where r+%3E+0 Is the nth term of a geometric sequence.
compare to general formula:T%5Bn%5D=T%5B1%5Dr%5E%28n-1%29

If the third term T%5B3%5D=48, we know that n=3, so we have
48=3r%5E%283-1%29
48%2F3=r%5E2
16=r%5E2
r=sqrt%2816%29
r=4