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Mathematics

(x + 3), 1, (3x − 7) and −5 are in proportion. The value of x is :

  1. −1

  2. 1

  3. −5

  4. 5

Ratio Proportion

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Answer

Given,

(x + 3), 1, (3x − 7) and −5 are in proportion.

∴(x+3)1=(3x−7)−5⇒(x+3)=(3x−7)−5⇒−5(x+3)=(3x−7)⇒−5x−15=3x−7⇒−5x−3x=15−7⇒−8x=8⇒x=−88⇒x=−1.\therefore \dfrac{(x + 3)}{1} = \dfrac{(3x - 7)}{-5} \\[1em] \Rightarrow (x + 3)= \dfrac{(3x - 7)}{-5} \\[1em] \Rightarrow -5(x + 3) = (3x - 7) \\[1em] \Rightarrow -5x - 15 = 3x - 7 \\[1em] \Rightarrow -5x - 3x = 15 - 7 \\[1em] \Rightarrow -8x = 8 \\[1em] \Rightarrow x = -\dfrac{8}{8} \\[1em] \Rightarrow x = -1.

Hence, option 1 is the correct option.

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