Question 436260
log(base 10)X+log(base 10)(X+1) = log(base 10)12
log(base 10)X(X+1) = log(base 10)12
X(X+1) = 12
X^2+X = 12
X^2+X-12 = 0
(X+4)(X-3) = 0
X = {-4,3}
Throw out the negative solution (extraneous) leaving:
X = 3