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Grade 11Algebra

If the ratio of H.M and G.M of two numbers is 12:13 , then the ratio of the numbers is?

Question image for If the ratio of H.M and G.M of two numbers is 12:1
Profile image of Piyush Upadhyay
8 Years agoGrade 11
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1 Answer

Profile image of Khimraj
8 Years ago
Let numbers are a and b. then
HM = 2ab/(a+b)
GM = \sqrt{ab}
HM/GM = 12/13
2\sqrt{ab} /(a+b) = 12/13
(a+b)/\sqrt{ab} = 13/6
\sqrt{a/b} + \sqrt{b/a} = 13/6
Let \sqrt{a/b} = x.then
x + 1/x = 13/6
6x2 – 13x + 1=0
x = 2/3 or 3/2
a/b = x2 = 4/9 or 9/4.
So correct option is (D) 4/9.
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