Question

By direct use of the definition of a derivative, the derivative of

f(x) = 1/x


?

Answer 1

1/(x+h) - 1/x

(x - x - h)/(x^2+xh)

-h/(x^2+xh)

divide by h
-1/(x^2+xh)

let h--->0
-1/x^2 sure enough