Answers

2016-07-13T17:56:07+08:00
7, _ , 63
Given: a1 = 7, an = 63, n = 3, r = ?

Solving for r:
an = a1 ⚫r^(n-1)
63 = 7 ⚫ r^(3-1)
63 = 7r^2
r^2 = 63/7
√(r^2) = √(9)
r = 3

a2 = a1 x r
a2 = 7 × 3
a2 = 21

*The geometric mean is 21.
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