The second and seventh term of a g.p are 9 and 1/2 respectively.find the common ratio, first term and 10th term

a, a r, a r^2, ...... a r^(n-1)

a r = 9
a r^6 = 1/2
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a = 9/r
(9/r) r^6 = 1/2
9 r^5 = 1/2
r^5 = 1 /18