㏒（10x）+1=3㏒x.求x的值.

㏒（10x）+1=3㏒x.求x的值.

3log(x) - log(10x) = 1
log(x^3) - log(10x) = log(10)
log[ (x^3) / (10x) ] = log(10)
x^2 / 10 = 10
x^2 = 100
x = ±10
因 x > 0
所以 x = 10