Find the derivative of the following functions from first principle:
(i) -x (ii) `(-x)^(-1)` (iii) `sin(x+1)` (iv) `cos(x-(pi)/(8))`

Explanation

(i)let `f(x)=x`


we need to find the derivative of `f(x)`


we know that `f'(x)=lim_(h->0)(f(x+h)-f(x))/h`


`f'(x)=lim_(h->0)((x+h)-(x))/h`


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