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Find three numbers in the ratio 2 : 3 : 5, the sum of whose squares is 608. - Mathematics

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Question

Find three numbers in the ratio 2 : 3 : 5, the sum of whose squares is 608.

Sum

Solution

Let the numbers be 2x, 3x and 5x

According to question,

(2x)2 + (3x)2 + (5x)2 = 608 

⇒ 4x2 + 9x2 + 25x2 = 608

⇒ 38x2 = 608

⇒ `x^2 = 608/38 = 16`

⇒ `x = sqrt(16)` 

Now, 16 = 2 × 2 × 2 × 2 = (2 × 2)2

⇒ `sqrt(16) = 2 xx 2 = 4`

∴ `x = sqrt(16) = 4`

Hence, the numbers are 2 × 4, 3 × 4, 5 × 4, i.e. 8, 12 and 20.

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Chapter 3: Square-Square Root and Cube-Cube Root - Exercise [Page 96]

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NCERT Exemplar Mathematics [English] Class 8
Chapter 3 Square-Square Root and Cube-Cube Root
Exercise | Q 130. | Page 96

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