[latex] sqrt[4]{x^3}=x^{ frac{3}{ 4} } [/latex]

I assume you meant the fourth root of  x raised to the third power. Rule ((a^b)^c)^d =  a^(a*b*c)  So in this case: x^3^(1/4) x^(3*1/4) x^(3/4)