How do you get the square root of 144

The expression 6x2 gives the surface area of a cube, and the expression x3 gives the volume of a cube, where x is the length of one side of the cube. find the surface area and the volume of a cube with a side length of 6m

Anyone know these questions? i need ,.

Solve the inequaliy: (x^2+2)(x−2)^2(6−2x)> 0