Given f(x)=x+x+x+…f(x) = \sqrt{x + \sqrt{x + \sqrt{x + \dots}}}f(x)=x+x+x+…, find xxx if f(x)=6f(x) = 6f(x)=6.
x=30x = 30x=30
x=36x = 36x=36
x=42x = 42x=42
x=20x = 20x=20