log base 2(x-1)+log base 2(x+1)=3, what is x and why. I get two different answers.

Question

log base 2(x-1)+log base 2(x+1)=3, what is x and why.  I get two different answers.

anonymous · Answer

write out that left side in terms of one log:

logbase2 [(x-1)(x+1)] = 3

so now you can write this out in exponential form:

2^3 = (x-1)(x+1)

anonymous · Answer

solve this quadratic..

anonymous · Answer

this how you got your answer?  and what are your answers?

anonymous · Answer

one answer was 2 and the other answer was 3.  I get when using your method

anonymous · Answer

I get 3 using your method

anonymous · Answer

well, solving that quadratic yields two solutions but 1 of those solutions need to be thrown out because it is not a solution to the original equation.  so there is only 1 solution.. x=3.

anonymous · Answer

thank you.

anonymous · Answer

yw... :)