I'm afraid even this basic a grasp of tensors is lost to me. What exactly is a tensor in the first place? I don't think I can answer your initial question concerning the fundamental definition of a rank two tensor.
Is it a matrix? I've learned that a tensor of rank 0 is a scalar and that a tensor of rank 1 is a vector, but I'm not sure I fully understand what exactly tensors are supposed to represent.
Homework Statement
If f(x) is a scalar-valued function, show that ∂ƒ²/∂xi∂xj are the components of a Cartesian tensor of rank 2.
Homework Equations
N/A
The Attempt at a Solution
I don't even know where to begin. We began learning tensors in multivariable calculus (though I don't think this is...