find x from log3 x-3log3 x=2

Answer 1

if you let y = log3x, you have
y - 3y = 2
y = -1
so, log3 x = -1
x = 3^-1 = 1/3

Answer 2

I assume you mean:
log₃ x-3log₃ x=2
then
log₃ x - log₃ x^3 = 2
log₃ (x/x^3) = 2
log₃ (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