Differentiation of Squared functions (1 Viewer)

[Sy123]

Now say in the 2U test tommorow we are given the generic maxima minima with something that is a pain to differentiate due to multiple chain rules etc.

Say that differential is:



But because it may contain square roots and stuff, I will square u



Now u and u^2 have the same x values for their maxima/minima.

Am I allowed to do this without any prior justification (like proving it or something).
Or can I just do it straight away