What is the value of ab,
If log4 log4 4a - b = 2 log4 (a - b) + 1
Explanation:
log4 log4 4a - b = 2log4 a-b + 1
∴ log4 (a - b) log4 4 = 2log4 a-b + 1
∴ log4 (a - b) = 2log4 a-b + 1
∴ log4 (a - b) = 2log4 a-b2 + 1
∴ log4 a-ba-b2 = 1
∴ a-ba+b-2ab = 4
∴ a - b = 4a + 4b - 8ab
∴ 8ab = 3a + 5b
∴ 8 = 3ab + 5ba
Let ab = x
∴ 8 = 3x + 5x
∴ 8x = 3x2 + 5
∴ 3x2 - 8x + 5 = 0
∴ 3x2 – 3x – 5x + 5 = 0
∴ 3x(x – 1) – 5(x – 1) = 0
∴(3x – 5)(x – 1) = 0
∴ x = 53 or x = 1
But x ≠ 1 as a ≠ b
∴ x ≠ 5/3
∴ ab = 53
Hence, option (c).
» Your doubt will be displayed only after approval.
Help us build a Free and Comprehensive Preparation portal for various competitive exams by providing us your valuable feedback about Apti4All and how it can be improved.