log3x+4=log 729 find the value of x
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Answered by
2
Log(729/3x)=4
Taking antilog at both sides
We have
243/x=10000
x= 243/10000= .0243
prabhushettisan:
NO NOT LIKE THAT
3X+4 IS UP TO LOG
Put it under bracket then!!
Answered by
1
It is not clear if the 4 is with in logarithm or outside :
if the question is Log (3x+4) = Log 729 => 3x+4 = 729 x = 725/3
Otherwise see below:
=====================================
Let us assume that given logarithms are with respect to 10.
Log 3 x + 4 = Log 729 = Log 9³ = Log 3⁶
(Log 3 + Log x) + 4 = 6 Log 3
Log x = 5 Log 3 - 4 = Log 3⁵ - 4 Log 10 = Log 243 - Log 10⁴ = Log (243 /10,000)
Removing the logarithms, x = 243/10,000 = 0.0243
=====================================
Alternately,
Log 3x + 4 = Log 729
Log 3x = Log 729 - 4 = Log 729/10,000
3x = 729/10,000
x = 243/10,000
if the question is Log (3x+4) = Log 729 => 3x+4 = 729 x = 725/3
Otherwise see below:
=====================================
Let us assume that given logarithms are with respect to 10.
Log 3 x + 4 = Log 729 = Log 9³ = Log 3⁶
(Log 3 + Log x) + 4 = 6 Log 3
Log x = 5 Log 3 - 4 = Log 3⁵ - 4 Log 10 = Log 243 - Log 10⁴ = Log (243 /10,000)
Removing the logarithms, x = 243/10,000 = 0.0243
=====================================
Alternately,
Log 3x + 4 = Log 729
Log 3x = Log 729 - 4 = Log 729/10,000
3x = 729/10,000
x = 243/10,000
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