
Sean M. answered 04/23/20
PhD Student in Mathematics
a)
i) Critical points are when f'(x)=0, or visually, where the graph may "peak" or "dip" or otherwise change. Here, we see there are no points where the derivative equals 0, so x does not exist.
ii) We see from the graph that f(x) is increasing across the interval (-∞,+∞).
iii) As there are no critical points, there are no relative maxima or minima.
b)
i) Here, we do have a critical point. We can see that at x=3/2, the graph changes from decreasing to increasing.
ii) The graph appears to be decreasing from (-∞,2] and then increasing from [2,+∞)
iii) As we do have a well-defined point such that f'(x)=0, namely x=3/2, we will also have a relative maximum or minimum. Looking at the graph, we can see that this is a relative minimum.
c)
i) Here we have two critical numbers, located at x=1/2 and x=3/2
ii) Increasing: [1/2,3/2]
Decreasing: (-∞,1/2]∪[3/2,+∞]
iii) Relative minimum: x=1/2
Relative maximum: x=3/2
d)
i) x=-1/2, 1, 2
ii) Increasing: (-∞,-1/2]∪[1,2]
Decreasing:[-1/2,1]∪[2,∞]
iii)x has local maxima at x=-1/2,2
x has a local minimum at x=1