- #1
Elus
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Homework Statement
Problem 1:
Solve log(x^3) = (log(x))^2 for x.
Note, there are two solutions, A and B, where A < B.
A = ?
B = ?
Problem 2:
Rewrite the expression 2log(x)-2log(x^2+1)+4log(x-1) as a single logarithm log A.
A = ?
2. The attempt at a solution
Problem 1 Attempt:
I might be able solve this graphically by plotting y1 = log(3^x) and y2 = (log(x))^2 and finding the points of intersection.
However, I'd like to do this by hand, if possible! Would I start by raising both sides to e?
e^log(x^3) = e^(logx)^2
then
x^3 = e^2
then
x = (e^2)^(1/3)
x = e^(2/3)
x = 1.947734
Wolfram-alpha says otherwise :( and there are supposed to be 2 solutions. I only got one D:
Problem 2 attempt:
Okay, I tried using properties of logarithms here.
2log(x)-2log(x^2+1)+4log(x-1)
2log(x) - 8*log(x^3 - x^2 + x - 1) <------- Since the 2 logs are added, you can
multiply the insides of the logs together, right?
16*log(x/(x^3-x^2+x-1)) <------------ Since the 2 logs are subtracted, you can
divide them, right?
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