 Hello and welcome to the session. The question says, find the derivative of the following functions from the first principles. First one is minus x. So before we find the derivative with the help of first principle, first let us learn the first principle of derivative. Suppose f is a real valued function, then the function defined by a limit as h approaches to 0 f at x plus h minus fx upon h, wherever the limit exists is defined to be the derivative of f at x and is denoted by f dash x. So this definition of derivative is called the first principle of derivative and this we shall be using to find the derivative of minus x. So this is a key idea. Let us begin with the solution. Let fx is equal to the given function minus x. Therefore f at x plus h is equal to minus of x plus h. Now let us find f dash x which is given by limit as h approaches to 0 f at x plus h minus fx upon h, this is further equal to limit as h approaches to 0 f at x plus h is minus of x plus h minus of fx is minus x upon h, this is further equal to limit as h approaches to 0 minus x minus h plus x upon h minus x plus x on cancelling we have limit as h approaches to 0 minus h upon h which on further cancelling we have limit as h approaches to 0 minus 1. Now minus 1 is independent of h therefore our answer is minus 1. Thus derivative of minus x with the help of first principle is minus 1. So this completes the session. Have a good day.