Answer to 3.6.1 all unsolved subparts

Answer to 3.6.1 (b) :

Differentiating, we get :

Now we need to factorize this. By trail and error, we find that derivative of f(x) is zero when x=1 and hence (x-1) is a factor of it. Using long division by (x-1) we obtain :

Equating the derivative with zero, we get the critical points as follows :
x1=1, x2=2 and x3 = 3

Now I know you can do the rest ;)

Answer to 3.61 (d) :

To make the evaluation simple, let's subtract both sides by -1 and then the equation becomes :

 Differentiating, we get :

Equating it with zero, we get :
x=7/5
Now do the rest for yourself.