(3) Find the maxima and minima of the function
.
We get
for maximum or minimum; or
and .
There is only one value, hence only one maximum or minimum.
it is therefore a minimum. (It is instructive to plot the graph of the function.)
(4) Find the maxima and minima of the function . (It will be found instructive to plot the graph.)
Differentiating gives at once (see example No. 1, p.68)
.
for maximum or minimum.
Hence and , the only solution
For , .
For , , so this is a maximum.