First, we'll have to precise that we work with decimal
logarithms.
Now, we'll use the power property of
logarithms:
3log x = log
x^3
2 log 3x = log
(3x)^2
Now, we'll re-write the
equation:
log x^3 + log (3x)^2 =
3
Because the bases of logarithms are matching, we'll use
the product property of logarithms: the sum of logarithms is the logarithm of the
product.
log x^3 + log (3x)^2 = log
[x^3*(3x)^2]
log [x^3*(3x)^2] =
3
We could write the term from the right side
as:
3 = 3*1 = 3* log10
The
equation will become:
log [x^3*(3x)^2] = 3*
log10
log [x^3*(3x)^2] =
log10^3
Because the bases are matching, we'll use the one
to one property:
x^3*(3x)^2 =
1000
9*x^(3+2) = 1000
9x^5 =
1000
We'll divide by 9:
x^5 =
1000/9
x^5 = 111.111 approx.
x
= (111.111)^1/5 approx.
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