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The sum of two numbers is 8 and 15 times the sum of their reciprocals is also 8. Find the numbers.

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The sum of two numbers is 8 and 15 times the sum of their reciprocals is also 8. Find the numbers.

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Let the numbers be x and 8 − x

Given that the sum of these numbers is 8

And 15 times the sum of their reciprocals as 8

`rArr15(1/x+1/(8-x))=8`

`rArr15(((8-x)+x)/(x(8-x)))=8`

⇒ 15 ((8 − ЁЭСе) + ЁЭСе) = 8(ЁЭСе(8 − ЁЭСе))

⇒ 15 [8 − ЁЭСе + ЁЭСе] = 8ЁЭСе(8 − ЁЭСе)

⇒ 120 = 64x − 8x2

⇒ 8ЁЭСе2 − 64ЁЭСе + 120 = 0

⇒ 8[ЁЭСе2 − 8ЁЭСе + 15] = 0

⇒ ЁЭСе2 − 5ЁЭСе − 3ЁЭСе + 15 = 0

⇒ (ЁЭСе − 5) (ЁЭСе − 3) = 0

⇒ x = 5 or x = 3

∴ The two numbers are 5 and 3.

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рдЕрдзреНрдпрд╛рдп 5: Quadratic equations - Exercise 5E [рдкреГрд╖реНрда репрез]

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