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Question
If three quantities are in continued proportion, show that the ratio of the first to the third is the duplicate ratio of the first to the second.
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Solution
Let x, y and z are the three quantities which are in continued proportion
Then, x : y :: y : z => y2 = xz
Now, we have to prove that
x : z = x2 : y2
⇒ xy2 = x2z
LHS
= xy2 = x(xz) = x2z = RHS
LHS = RHS
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