Hi there, I am doing some tutorial questions and we are doing single variable optimisation. Essentially, the solutions show to factorise however they seem to expand in square roots to find the stationary points and I want to know why and how they have done this. Please see attached screenshot.

2. f(.7:) = 335 5$3,$ E [1,\\/5] (a) Stationary points in (1, J5) f'(:r) = 5x4 15:332 f'(9:) =0 4:) 59.72 (323) =0 522(2 30:: + V3) = 0 . . f(:c) has three stationary points at x = {x/g, V5}. Since \\/ g (1, J5), there are only two stationary points in (1,\\/5)