1.

Find the value of x, if log5 (x - 2) + log5 (x + 3) = log5 14.1. 22. 33. 44. 5

Answer» Correct Answer - Option 3 : 4

CONCEPT:

  • Logarithmic product rule is represented as log p (x) + log p (y) = log p (x.y)
  • Log is not defined for negative values.

 

CALCULATION:

Given that log5 (x - 2) + log5 (x + 3) = log5 14

Dropping log from the both sides we get- 

⇒ (x - 2) × (x + 3) = 14

⇒x2 + x - 6 = 14

⇒ x2 + x - 20 = 0

On solving the quadratic equation

x2 + x - 20 = 0

⇒ (x - 4) × (x + 5) = 0

⇒ x = 4 and x = - 5

Therefore x = 4. (negative value of x will be excluded)

Therefore, option (3) is the correct answer.



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