Two charge carriers in the Drude model

[Mythbusters]

I'm studying Solid State Physics and I have some problems with a problem.

It is stated like this:

Consider a system of two charge carriers in the Drude model. The two carriers have the same density n and opposite charge (e and-e), and their masses and relaxation times are m1,m2 and r1,r2 respectively.
(a) Calculate the magnetoresistance ∆ρ=ρ(B)-ρ(0), B is the magnetic induction.
(b) Calculate the Hall coefficient.
Hint: Consider the conductivity tensor of the combined system of the carriers

I don't know how to begin with this problem, wonder if someone please can help me?

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[NateD]

The Drude model is a classical model of electron motion in a metal. It is described by a set of equations which describe the motion of electrons in the presence of an electric field and a magnetic field. In particular, these equations can be used to calculate the magnetoresistance and the Hall coefficient. For part (a), you will need to calculate the conductivity tensor of the combined system of carriers. This is done by solving the Drude model equations for the conductivity tensor for each charge carrier, then summing the results. Once you have the conductivity tensor, you can calculate the magnetoresistance ∆ρ by using the equation ∆ρ=ρ(B)-ρ(0). For part (b), you can calculate the Hall coefficient by using the equation RH=σyx/σxx, where σyx is the off-diagonal element of the conductivity tensor and σxx is the diagonal element of the conductivity tensor. I hope this helps!