Let its two roots be x 1, x2, then x 1x2= (root number 3) k: y =-(√ 3/3) x+b.

When y=0, the angle between b/x=(√3)/3 ∴ straight line AC and X axis is 30.

∴ AB = X 1/COS30 = (root number 3) x1/2; Ac = x2/cos30 = (root number 3) x2/2;

∴ AB*AC=x 1*x2*[ (root number 3)/2] = x 1 * x2 * 4/3 and AB*AC=4.

∴x 1x2=3 and x 1x2= (root number 3)k ∴k= root number 3.