code: function nthRoot(num, nArg, precArg) { // : Int -> Int -> Int -> Int
    var n = nArg || 2;
    var prec = precArg || 12;
   
    var x = 1; // Initial guess.
    for (var i=0; i<prec; i++) {
      x = 1/n * ((n-1)*x + (num / Math.pow(x, n-1)));
    }
   
    return x;
  }
docs: general nth root-ing