Question

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

Answer 1

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)

Answer 2

solve this quadratic..

Answer 3

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

Answer 4

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

Answer 5

I get 3 using your method

Answer 6

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.

Answer 7

thank you.

Answer 8

yw... :)