Question 45455This question is from textbook intermediate algebra
: Sove the logarithmic equation, could you explain to me how to do this?
log x + log (x+9) = 1
This question is from textbook intermediate algebra
Answer by stanbon(75887)   (Show Source):
You can put this solution on YOUR website! log x + log (x+9) = 1
You have a log rule which says log a + log b = log ab
So, you write:
log x(x+9) =1
You know a transformation which says
log b = c means the same as b=10^c
So you write:
x(x+9)=10^1
x^2+9x-10=0
(x+10)(x-1)=0
Cheers,
Stan H.
x=-10 or x=1
You check these answers in the original equation
and see that x=-10 cannot be a solution because you
cannot have the log of a negative number.
So, x=1 is the only solution of your original equation.
Cheers,
Stan H.
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