How do you solve log_3 (x + 3) + log_3 (x + 5) = 1?

1 Answer
Dec 6, 2015

x=-2

Explanation:

log(base3)(x+3)+log(base 3)(x+5)=1-> use product rule of logarithm

log(base3)((x+3)(x+5))=1 write in exponential form

3^1=(x+3)(x+5)
x^2+8x+15=3
x^2+8x+12=0
(x+6)(x+2)=0

x+6=0 or x+2=0

x=-6 or x=-2

x=-6 is extraneous . An extraneous solution is root of transformed but it is not a root of original equation.

so x=-2 is the solution.