Find a and r for the geometric sequence with the given terms.
a4 = 51.2 and a7 = 26.2144
Find the ratio between the given terms:
Since there are 3 multiplications between these terms, take the third root to get r:
r = (0.512)1/3 = 0.8
Plug things into the geometric sequence formula.
an = arn – 1
a4 = ar3
51.2 = a(0.8)3
We conclude that