March 4th, 2016, 02:39 PM  #1 
Newbie Joined: Feb 2016 From: Oregon Posts: 19 Thanks: 0  Logarithms
I need help solving this problem: Find the solution(s) of the logarithmic equation log2(x2−5x−20)=2 Thanks! 
March 4th, 2016, 02:50 PM  #2 
Global Moderator Joined: Dec 2006 Posts: 20,480 Thanks: 2039 
Did you mean $\log_2$(x²  5x  20) = 2? That would imply x²  5x  20 = 4.

March 4th, 2016, 02:58 PM  #3 
Math Team Joined: Jan 2015 From: Alabama Posts: 3,264 Thanks: 902 
Yes, this is a very difficult problem if you don't know what "log" means! In general, $\displaystyle log_a(x)= y$ is equivalent to $\displaystyle x= a^y$. In particular, $\displaystyle log_2(x)= 2$ is equivalent to $\displaystyle x= 2^2= 4$ 

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