Question
find x from log3 x-3log3 x=2
Answers
oobleck
if you let y = log3x, you have
y - 3y = 2
y = -1
so, log3 x = -1
x = 3^-1 = 1/3
y - 3y = 2
y = -1
so, log3 x = -1
x = 3^-1 = 1/3
Reiny
I assume you mean:
log<sub>3</sub> x-3log<sub>3</sub> x=2
then
log<sub>3</sub> x - log<sub>3</sub> x^3 = 2
log<sub>3</sub> (x/x^3) = 2
log<sub>3</sub> (1/x^2) = 2
1/x^2 = 3^2 = 9
9x^2 = 1
x = ± 1/3, but log (-1/3) would be undefined, so
x = 1/3
log<sub>3</sub> x-3log<sub>3</sub> x=2
then
log<sub>3</sub> x - log<sub>3</sub> x^3 = 2
log<sub>3</sub> (x/x^3) = 2
log<sub>3</sub> (1/x^2) = 2
1/x^2 = 3^2 = 9
9x^2 = 1
x = ± 1/3, but log (-1/3) would be undefined, so
x = 1/3