Question

max value of X?, such that root X greater or equal to 3X

Answer 1

$\sqrt x \geq 3x\qquad (x\geq 0)\\x\geq9x^2\\9x^2-x\leq0\\x(9x-1)\leq0\\x\in\left\langle0,\dfrac{1}{9}\right\rangle$

$x_{\text{max}}=\dfrac{1}{9}$