Limit Definition of Derivative

Use the definition of derivatives to find the derivative of the following function,

$f(x) = \sqrt{x - 1}$

Find the slope of the tangent line to

$f(x) = \sqrt{x}$

when x = 1

Find the slope of the tangent line to

$f(x) = \frac{1}{x}$

when x = 4

Use the definition of the derivative to find $f\prime(x)$ if

$f(x) = \frac{2}{3 - 5x}$