Let A be a n x m matrix. Show that if the function y = f(x) defined for m x 1 matrices x by y = Ax satisfies the linearity property, then f(aw + bz) = af(w) + bf(z) for any real numbers a and b and any m x 1 matrices w and z.

This is what I did

Scalars - k1, k2

Vectors - u, v

Matrix - n x m matrix

f(aw + bz) = af(w) + bf(z)

A(k1u + k2v) = k1Au + k2Av

m x 1 matrices are the vectors u and v

multiplying scalars to vectors:

mk1 x k1 matrix

mk2 x k2 matrix

I'm not understanding how I am supposed to prove that this function is linear.