Question

If x + y = 12 and xy = 27 ; find the value of x
3 + y
3

Answer 1

★Given:-

x+y=12

xy=27

★To find:-

Value of x

★Solution

xy = 27

y = 27/x

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Substituting the value of y in x + y = 12 will give,

x + 27/x = 12

Multiplying the equation by x will give,

x² + 27 = 12x

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Factorising the equation will give,

x² + 27 = 12x

x² - 12x + 27 = 0

We need two numbers such that, on Multiplying, we get 27 and on adding, we get -12.

The numbers are - 3 and -9

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x² - 3x -9x + 27

x(x-3) - 9(x-3)

(x-3)(x-9)

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x - 3 = 0

x = 3

Or

x - 9 = 0

x = 9

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Hope it helps