Question 29760
logb n = p   or   b^p = n
b is the base
p is the power
n is the answer
when adding logs of the same base ... you are really multiplying.

log2x + log2(x-3)=2
log2 x(x-3) =2
transform this into the b^p = n form
{{{2^2 = x(x-3)}}} square 2 and distribute the x to (x-3)
{{{4 = x^2 - 3x}}} subtract 4 from both sides
{{{0 = x^2 - 3x - 4}}} factor
{{{0 = (x-4)(x+1)}}} set each quantity equal to zero
0=x-4   or    0=x+1 
x=4          -1=x