- #1
Karol
- 1,380
- 22
Homework Statement
Homework Equations
At local minimum or maximum the first derivative equals zero
The Attempt at a Solution
a) $$f'=2x-\frac{a}{x^2},~~2\cdot 2-\frac{a}{4}=0~\rightarrow a=16$$
Near 0 from the left a/x gets large negative values, smaller than for a=16. that's my proof for the local minimum.
The same for b).
But how to prove c)?
If a>0, f'<0 for x<0. so f decreases. for x>0 we found a minimum, and f''>0, so it holds water.
Similar reasoning for a<0. is this the way?