Linear Transformation T : M22 & Finding Ker T Dimension

[Nope]

Quick please! T(A) = Tr(A)

Homework Statement

Let T : M₂₂ define as T(A) = Tr(A). Show that T is a linear transformation
and find the dimension of ker T.

Homework Equations

The Attempt at a Solution

what is Tr(A)?
is it trace(A), or rT(A) , r is a real number?

 

[micromass]

It's most likely the trace.