Answers

2016-07-31T15:53:05+08:00
The answer is x = ±4
Solution: 
12, 9x, 108 form a geometric sequence
Solve for x:
Since by the definition of a geometric sequence,
9x over 12 should be equal to 108 over 9x
We could simplify it further as 3x/4 = 12/x
Thus, by cross multiplication, we'll get 3x^2 = 48
Divide both sides by 3, x^2 =16
Get the square root of 16 to determine x, the answer is x = ±4
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