First, let's impose the constraints of existence of
logarithms:
x+2>0
x>-2
and
3x+1>0
3x>-1
x>-1/3
The
common interval of values that satisfies both constraints is (-1/3 ,
+inf.).
Now, we can solve the equation by subtracting both
sides the value ln(x+2).
We'll
get:
- ln (3x + 1) = 4 -
ln(x+2)
We'll multiply both sides by
-1:
ln (3x + 1) = -4 +
ln(x+2)
We'll write -4
as:
-4*1 = -4*ln e = ln
(e^-4)
We'll re-write the
equation:
ln (3x + 1) = ln (e^-4) +
ln(x+2)
We'll apply the product property to the right side
of the eq.:
ln (3x + 1) = ln
[(e^-4)*(x+2)]
Because the bases of the logarithms are
matching, we'll apply one to one property:
3x+ 1 = x/e^4 +
2/e^4
We'll subtract both sides
x/e^4:
3x - x/e^4 + 1 =
2/e^4
We'll re-write the
eq.:
3x*e^4 - x = 2 -
e^4
We'll factorize to the left
side:
x*(3e^4 - 1) =
2-e^4
We'll divide by (3e^4 -
1):
x = (2-e^4)/ (3e^4 -
1)>-1/3
So, the solution is
admissible!
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