just use the formulas you have:
T12 = ar^11 = 49
T14 = ar^13 = 2401
T14/T12 = r^2 = 49
so, r = 7 or -7
T15 = T14 * r = 16807 or -16807.
Can't tell, since we don't know whether r is 7 or -7.
the 12th term in a geometric sequence is 49, and the 14th term is 2401 . Find the 15th term
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