Question 13The angle bisector of the acute angle formed at the origin by the graphs of the lines $y = x$ and $y = 3x$ has equation $y = kx.$ What is $k?$$\dfrac{1 + \sqrt{5}}{2}$$\dfrac{1 + \sqrt{7}}{2}$$\dfrac{2 + \sqrt{3}}{2}$$2$$\dfrac{2 + \sqrt{5}}{2}$