CAT 2017 Slot 2 — QA Question 22
LogarithmsEasy
If x is a real number such that log35 = log5(2 + x), then which of the following is true?
Answer & solution
- A
0 < x < 3
- B
23 < x < 30
- C
x > 30
3 < x < 23
Solution
Given log35 = log5(x + 2)
Now log33 < log35 < log39
∴ 1 < log35 < 2
⇒ 1 < log5(x + 2) < 2
⇒ log55 < log5(x + 2) < 2log55
⇒ log55 < log5(x + 2) < log525
⇒ 5 < 2 + x < 25
⇒ 3 < x < 23
Hence, option (d).