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X+4,x+12,x-1 and x+5 are in proportion.find the value of x

User Aknay
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1 Answer

7 votes

Answer:

Explanation:

As they are in proportion,

x +4 : x +12 :: x -1 : x + 5

Product of means = Product of extremes

(x + 12)(x -1) = (x +4)(x+5)

Use FOIL method for polynomial multiplication

x*x + x*(-1) + 12*x + 12*(-1) = x*x + x*5 + 4*x + 4*5

x² - x + 12x - 12 = x² + 5x + 4x + 20

Combine like terms

x² + 11x - 12 = x² + 9x + 20

x² + 11x - 12 - x² - 9x - 20 = 0

Combine like terms

x² - x² + 11x -9x -12 -20 = 0

2x - 32 = 0

2x = 32

x = 32/2

x = 16

User Andilabs
by
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