SOLUTION: 39. lnx+lnx^2=3 The answer is {e}, but hot did they get that? 41. logx+log(x-21)=2 The answer is {25}, but how did they get that?

Question 135862This question is from textbook A Graphical Approach to College Algebra
: 39. lnx+lnx^2=3
The answer is {e}, but hot did they get that?
41. logx+log(x-21)=2
The answer is {25}, but how did they get that? This question is from textbook A Graphical Approach to College Algebra

Answer by stanbon(75887) (Show Source): You can put this solution on YOUR website!
39. lnx+lnx^2=3
ln(x^3) = 3
x^3 = e^3
x = e
------------------
The answer is {e}, but hot did they get that?
-----------------------
41. logx+log(x-21)=2
log(x(x-21)) = 2
log(x^2-21x) = 2
x^2-21x=10^2
x^2-21x-100 = 0
(x-25)(x+4) = 0
x=25 or x=-4
But x cannot be -4 as that would give you log(-4) in the problem;
log(-4) is meaningless.
=============================
Cheers,
Stan H.
The answer is {25}, but how did they get that?

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