Answer:
(a) 
(b) 
Step-by-step explanation:
The given function is
.... (1)
According to the first principle of the derivative,






Cancel out common factors.

By applying limit, we get


.... (2)
Therefore
.
(b)
Put x=2, to find the y-coordinate of point of tangency.

The coordinates of point of tangency are (2,0.25).
The slope of tangent at x=2 is

Substitute x=2 in equation 2.

The slope of the tangent line at x=2 is -0.25.
The slope of tangent is -0.25 and the tangent passes through the point (2,0.25).
Using point slope form the equation of tangent is





Therefore the equation of the tangent line at x=2 is y=-0.25x+0.75.