[tex]\sqrt{36x^8y^4}\\\\=\left(6^2 x^8 y^4\right)^{\tfrac 12}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~;\left[\sqrt a = a^{\tfrac 12} \right]\\\\=\left(6^2\right)^{\tfrac 12} \cdot \left(x^8\right)^{\tfrac 12} \cdot \left(y^4\right)^{\tfrac 12}\\\\=6^{\tfrac 22} \cdot x^{\tfrac 82} \cdot y^{\tfrac 42}\\\\=6 x^4 y^2[/tex]
