Since the bases of the logarithms are matching, we'll
apply the product property:
log 2(x+1)+log2(x-2)=log2
[(x+1)(x-2)]
We'll re-write the
equation:
log2 [(x+1)(x-2)] =
2
We'll take
antilogarithms:
[(x+1)(x-2)] =
2^2
[(x+1)(x-2)] = 4
We'll
remove the brakets:
x^2 - x - 2 - 4 =
0
x^2 - x - 6 = 0
We'll apply
quadratic formula:
x1 = [1+sqrt(1 +
24)]/2
x1 = (1 + 5)/2
x1 =
3
x2 = -2
Since
the common interval of admissible values for x (values that make the logarithms to
exist) is (2 , +infinite), we'll reject the negative value and we'll keep as solution of
equation only x = 3.
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