Question 371941
log(x)+log(x+21)=2
log(x(x+21))=2
x(x+21) = 10^2
x^2+21x = 100
x^2+21x-100 = 0
Factoring the left:
(x+25)(x-4) = 0
.
x = {-25, 4}
We can throw out the -25 solution -- it is an extraneous solution leaving:
x = 4