How do you solve #logx+log(x+15)=2#?

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Answer 1 · 2015-02-04T19:58:13

Supposing the base of the log being #10# you can solve it by using:
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So you get (using also the definition of logarithm):

Answer 2 · 2015-02-04T20:07:36

There is an error.

The arguments of the logarithmics have to be positive.

So you had to put two condition:

#x>0#
#x> -15#

they drive us to #x>0#.

So, one of the solution you found (#-20#) is not acceptable!