Deriving minimum and maximum speeds on a banked circular curve

[fineztpaki]

Homework Statement

A circular curve of radius R in a new highway is designed so that a car traveling at speed v can negotiate the turn safely on glare ice (zero friction). If a car travels too slowly, then it will slip toward the center of the circle. If it travels too fast, then it will slip away from the center of the circle. If the coefficient of static friction increases, a car can stay on the road while traveling at any speed within a range from vmin to vmax. Derive formulas for vmin and vmax using mu for µ, and v, R, and g as appropriate.

Vmin= ?
Vmax= ?

Homework Equations

How can i derive a formula for this?

The Attempt at a Solution

I've tried a couple but I don't know exactly how to do it. When i put my answer it comes out wrong. help?

 

[fineztpaki]

I got for vmin:
Vsqrt((1-mu(Rg)/(V^2))/(1+mu(V^2)/(Rg)))
but it keeps saying its wrong!??!?