Advertisements
Advertisements
Question
Solve for x:
log (10x + 5) – log (x – 4) = 2
Sum
Advertisements
Solution
Given, log (10x + 5) – log (x – 4) = 2
⇒ log (10x + 5) – log (x – 4) = 2 log 10
⇒ `log (10x + 5)/(x - 4) = log 10^2`
⇒ `(10x + 5)/(x - 4) = 100`
⇒ 10x + 5 = 100 (x – 4)
⇒ 10x + 5 = 100x – 400
⇒ 100x – 10x = 405
⇒ 90x = 405
⇒ x = `405/90`
⇒ x = 4.5
shaalaa.com
Is there an error in this question or solution?
Chapter 7: Logarithms - MISCELLANEOUS EXERCISE [Page 77]
