Math Help - Computing the derivative

1. Computing the derivative

I have attached a problem. Can anyone help me out with a detailed solution.

2. Re: Computing the derivative

Hey Chandru1.

Are you aware of the modern definition of the derivative in n-dimensions?

3. Re: Computing the derivative

Yeah I am aware of the defintion. But I just need a detailed solution so that I can work out similarly other problem.

4. Re: Computing the derivative

Have you looked at how they derive the modern definition of the derivative (like in Spivaks Calculus on Manifolds)?