Question 585055
Let f(x) = 3x. 
Find f(3)
Sub 3 for x
f(3) = 3*3 = 9
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f(1/3)
Sub 1/3 for x
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and
Solve the equation  1296 x  = 6
x = 6/1296
x = 1/216
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last but not least 
Simplify the expression.    
3 log 3 (6x – 4)
If you mean
{{{3*log(3,(6x-4))}}}
= {{{log(3,(6x-4)^3)}}}
Not much simpler, if any.