Problem with equation / proving formula

[Trec93]

Homework Statement

I have to prove some formula, I got stuck in the process.

Homework Equations

Formula to prove:
v_{0} = \frac{M+m}{m}\sqrt{2gus}
Valid equation that should get me to this formula:
\frac{m^2v_{0}^2}{2(M+m)} = gmus

The Attempt at a Solution

v_{0}^2=\frac{2(M+m)}{m^2}gmus
v_{0}^2 = \frac{M+m}{m}2gus
v_{0} = \sqrt{\frac{M+m}{m}2gus}

I'm pretty sure my math has failed me here, that right handside of the equation seems fishy, or maybe book did a mistake?

 

[Let'sthink]

You seem to be correct may be there is a mistake in the book, what is u?

 

[Trec93]

Yeah I'm probably going to assume that there's a mistake in the book, u is the coefficient of friction, this equation is the given equation of kinetic energy = work where the force is the force of friction.