If m= log 20 and n = log 25, find the value of x, so that : 2 log (x - 4) = 2 m - n
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Answered by
45
m = log 20
n = log 25
so 2log (x - 4) = 2m - n
⇒ log (x - 4)² = 2log20 - log25
⇒ log(x - 4)² = log (20² / 25)
cancelling log from both sides
(x - 4)² = 20² / 25
⇒ x - 4 = 20 / 5
x = 4 + 4 = 8 ANSWER
n = log 25
so 2log (x - 4) = 2m - n
⇒ log (x - 4)² = 2log20 - log25
⇒ log(x - 4)² = log (20² / 25)
cancelling log from both sides
(x - 4)² = 20² / 25
⇒ x - 4 = 20 / 5
x = 4 + 4 = 8 ANSWER
samharsh:
answer is not correct. the correct answer is x = 8
Answered by
20
2log(x-4) = 2m-n
log (x-4)² = 2log20 - log 25
log (x-4)² = log20² - log25
log(x-4)² - log(20²/25)
⇒ (x-4)² = (20/5)²
x - 4 = 4
x = 8
log (x-4)² = 2log20 - log 25
log (x-4)² = log20² - log25
log(x-4)² - log(20²/25)
⇒ (x-4)² = (20/5)²
x - 4 = 4
x = 8
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