`(f(x)pm g(x))'=f'(x)pm g'(x)`
So by using the above rules we can differentiate our function, but first let's rewrite function `f` to get more convenient form.
So to calculate `f'(5)` you simply put 5 instead of `x.`
I have to point out that this is not rounded result, that is there are only 3 decimal places, no more.
Now to be able to graph the tangent at point `(5,3/25)` we must find equation of the tangent line which is given by formula:
Now to calculate `l` we simpliput all data we have into formula (1).
Blue line represents your function `f` while red line represents tangent at point `(5,3/25)`.