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If 7x – 15y = 4x + y, find the value of x : y. Hence, use componendo and dividend to find the values of: 3x2+2y23x2-2y2 - Mathematics

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Question

If 7x – 15y = 4x + y, find the value of x : y. Hence, use componendo and dividend to find the values of:

`(3x^2 + 2y^2)/(3x^2 - 2y^2)`

Sum

Solution

7x – 15y = 4x + y

7x – 4x = y + 15y

3x = 16y

`x/y = 16/3`

`=> x^2/y^2 = 256/9`

`=> (3x^2)/(2y^2) = (768)/18 = 128/3`  ...`("Multiplying both sides by" 3/2)`

`=> (3x^2 + 2y^2)/(3x^2 - 2y^2) = (128 + 3)/(128 - 3)`   ...(Applying componendo and dividendo)

`=> (3x^2 + 2y^2)/(3x^2 - 2y^2) = 131/125`

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Chapter 7: Ratio and Proportion (Including Properties and Uses) - Exercise 7 (D) [Page 102]

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Selina Mathematics [English] Class 10 ICSE
Chapter 7 Ratio and Proportion (Including Properties and Uses)
Exercise 7 (D) | Q 16.2 | Page 102

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