If f(x)=log3x, what if f(1/9)?

If your expression means:

f(x) = log ( 3 x )

then

f(1/3) = log ( 3 ∙ 1 / 9 ) = log ( 3 / 9 ) = log ( 1 / 3 ) = - log ( 3 )

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Remark:

log ( 1 ) = 0

log ( 1 / n ) = log ( 1 ) - log ( n ) = 0 - log n = - log ( n)

that's why

log ( 1 / 3 ) = - log ( 3 )
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My typo.

f(1/9) = log ( 3 ∙ 1 / 9 ) = log ( 3 / 9 ) = log ( 1 / 3 ) = - log ( 3 )

If you mean log base 3, f(x) = log_3(x), then

f(1/9) = -2, since 1/9 = 3^-2

To find the value of f(1/9) when f(x) = log3x, we need to substitute 1/9 into the equation.

f(x) = log3x

Substituting x = 1/9:

f(1/9) = log3(1/9)

Now, to evaluate log3(1/9), we can use the logarithmic property:

loga(b/c) = loga(b) - loga(c)

Applying this property to our equation:

log3(1/9) = log3(1) - log3(9)

The logarithm of 1 to any base is always 0:

log3(1/9) = 0 - log3(9)

Now, we can evaluate log3(9) using the logarithmic property again:

loga(a) = 1

So,

log3(9) = 1

Substituting this back into our equation:

log3(1/9) = 0 - 1

Simplifying, we get:

log3(1/9) = -1

Therefore, f(1/9) = -1.