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Mathematics

Three positive numbers are in the ratio 12:13:14.\dfrac{1}{2} : \dfrac{1}{3} : \dfrac{1}{4}. Find the numbers if the sum of their squares is 244.

Quadratic Equations

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Answer

Since, numbers are in ratio 12:13:14.\dfrac{1}{2} : \dfrac{1}{3} : \dfrac{1}{4}.

Hence, numbers are x2,x3,x4.\dfrac{x}{2}, \dfrac{x}{3}, \dfrac{x}{4}.

Given, sum of squares of number = 244.

(x2)2+(x3)2+(x4)2x24+x29+x216=24436x2+16x2+9x2144=24461x2=244×144x2=3513661x2=576x=576x=±24.\Rightarrow \Big(\dfrac{x}{2}\Big)^2 + \Big(\dfrac{x}{3}\Big)^2 + \Big(\dfrac{x}{4}\Big)^2 \\[1em] \Rightarrow \dfrac{x^2}{4} + \dfrac{x^2}{9} + \dfrac{x^2}{16} = 244 \\[1em] \Rightarrow \dfrac{36x^2 + 16x^2 + 9x^2}{144} = 244 \\[1em] \Rightarrow 61x^2 = 244 \times 144 \\[1em] \Rightarrow x^2 = \dfrac{35136}{61} \\[1em] \Rightarrow x^2 = 576 \\[1em] \Rightarrow x = \sqrt{576} \\[1em] \Rightarrow x = \pm 24.

Since numbers are positive,

x ≠ -24.

Numbers = x2=242=12,x3=243=8,x4=244=6.\dfrac{x}{2} = \dfrac{24}{2} = 12, \dfrac{x}{3} = \dfrac{24}{3} = 8, \dfrac{x}{4} = \dfrac{24}{4} = 6.

Hence, numbers are 6, 8, 12.

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