SOLUTION: {{{ (ln x)^2 + 2*(ln x) = 3 }}}

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Question 1095952: +%28ln+x%29%5E2+%2B+2%2A%28ln+x%29+=+3+
Found 3 solutions by KMST, ikleyn, MathTherapy:
Answer by KMST(5328) About Me  (Show Source):
Answer by ikleyn(52800) About Me  (Show Source):
You can put this solution on YOUR website!
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+%28ln+x%29%5E2+%2B+2%2A%28ln+x%29+=+3+
~~~~~~~~~~~~~~~~~

%28ln%28x%29%29%5E2 + 2%2A%28ln+x%29 = 3   ====>

%28ln%28x%29%29%5E2 + 2%2A%28ln+x%29 + 1 = 4   ====>

%28ln%28x%29%2B1%29%5E2 = 4  ====>

ln(x) + 1 = +/- 2  ====>


Case a):  ln(x) + 1 = 2  ====>  ln(x) = 1  ====>  x = e.


Case b):  ln(x) + 1 = -2  ====>  ln(x) = -3  ====>  x = e%5E%28-3%29.


Answer.  There are two solutions:  x = e   and   x = e%5E%28-3%29.



Answer by MathTherapy(10552) About Me  (Show Source):
You can put this solution on YOUR website!

+%28ln+x%29%5E2+%2B+2%2A%28ln+x%29+=+3+
matrix%281%2C3%2C+%28ln+%28x%29%29%5E2+%2B+2+ln+%28x%29%2C+%22=%22%2C+3%29
matrix%281%2C3%2C+%28ln+%28x%29%29%5E2+%2B+2+ln+%28x%29+-+3%2C+%22=%22%2C+0%29
matrix%281%2C3%2C+%28ln+%28x%29%29%5E2+%2B+3+ln+%28x%29+-+ln+%28x%29+-+3%2C+%22=%22%2C+0%29 ------ Replacing 2 ln (x) with 3 ln (x) – ln (x)
ln (x)[ln (x) + 3] – 1 [ln (x) + 3] = 0
[ln (x) – 1][ln (x) + 3] = 0
ln (x) – 1 = 0 OR ln (x) + 3 = 0
ln (x) = 1 OR ln (x) = - 3