Calculus/Differentiation/Applications of Derivatives/Exercises

Find the relative maximum(s) and minimum(s), if any, of the following functions.

1. ${\displaystyle f(x)={\frac {x}{x+1}}}$

2. ${\displaystyle f(x)={\sqrt[{3}]{(x-1)^{2}}}}$

3. ${\displaystyle f(x)=x^{2}+{\frac {2}{x}}}$

4. ${\displaystyle f(s)={\frac {s}{1+s^{2}}}}$

5. ${\displaystyle f(x)=x^{2}-4x+9}$

6. ${\displaystyle f(x)={\frac {x^{2}+x+1}{x^{2}-x+1}}}$

7. Show that the expression ${\displaystyle x+{\frac {1}{x}}}$ cannot take on any value strictly between 2 and -2.

Determine the absolute maximum and minimum of the following functions on the given domain

8. ${\displaystyle f(x)={\frac {x^{3}}{3}}-{\frac {x^{2}}{2}}+1}$ on ${\displaystyle [0,3]}$

9. ${\displaystyle f(x)=\left({\frac {4}{3}}x^{2}-1\right)x}$ on ${\displaystyle [-{\tfrac {1}{2}},2]}$

Find the intervals where the following functions are increasing or decreasing

10. ${\displaystyle f(x)=10-6x-2x^{2}}$

11. ${\displaystyle f(x)=2x^{3}-12x^{2}+18x+15}$

12. ${\displaystyle f(x)=5+36x+3x^{2}-2x^{3}}$

13. ${\displaystyle f(x)=8+36x+3x^{2}-2x^{3}}$

14. ${\displaystyle f(x)=5x^{3}-15x^{2}-120x+3}$

15. ${\displaystyle f(x)=x^{3}-6x^{2}-36x+2}$

Find the intervals where the following functions are concave up or concave down

16. ${\displaystyle f(x)=10-6x-2x^{2}}$

17. ${\displaystyle f(x)=2x^{3}-12x^{2}+18x+15}$

18. ${\displaystyle f(x)=5+36x+3x^{2}-2x^{3}}$

19. ${\displaystyle f(x)=8+36x+3x^{2}-2x^{3}}$

20. ${\displaystyle f(x)=5x^{3}-15x^{2}-120x+3}$

21. ${\displaystyle f(x)=x^{3}-6x^{2}-36x+2}$

22. You peer around a corner. A velociraptor 64 meters away spots you. You run away at a speed of 6 meters per second. The raptor chases, running towards the corner you just left at a speed of ${\displaystyle 4t}$ meters per second (time ${\displaystyle t}$ measured in seconds after spotting). After you have run 4 seconds the raptor is 32 meters from the corner. At this time, how fast is death approaching your soon to be mangled flesh? That is, what is the rate of change in the distance between you and the raptor?

23. Two bicycles leave an intersection at the same time. One heads north going ${\displaystyle 12{\rm {\,mph}}}$ and the other heads east going ${\displaystyle 5{\rm {\,mph}}}$ . How fast are the bikes getting away from each other after one hour?

24. You're making a can of volume ${\displaystyle 200{\rm {\,m^{3}}}}$ with a gold side and silver top/bottom. Say gold costs 10 dollars per ${\displaystyle {\rm {m^{2}}}}$ and silver costs 1 dollar per ${\displaystyle {\rm {m^{2}}}}$ . What's the minimum cost of such a can?

25. A farmer is investing in ${\displaystyle 216{\rm {\,cm}}}$ of fencing so that he can create an outdoor pen to display three different animals to sell. To make it cost effective, he used one of the walls of the outdoor barn as one of the sides of the fenced in area, which is able to enclose the entire area. He wants the internal areas for the animals to roam in to be congruent (i.e. he wants to segment the total area into three equal areas). What is the maximum internal area that the animals can roam in, given these conditions?

26. What is the maximum area of a rectangle inscribed (fitted so that the corners of the rectangle are on the circumference) inside a circle of radius ${\displaystyle r}$?

27. A cylinder is to be fitted inside a glass spherical display case with a radius of ${\displaystyle R=3{\rm {\,in}}}$. (The sphere will form around the cylinder.) What is the largest volume that a cylinder will have inside such a display case?

28. A ${\displaystyle 6\,{\rm {ft}}}$ tall man is walking away from a light that is ${\displaystyle 15}$-feet above the ground. The man is walking away from the light at ${\displaystyle 6}$ feet per second. How fast (speed not velocity) is the shadow, cast by the man, changing its length with respect to time?

29. A canoe is being pulled toward a dock (normal to the water) using a taut rope. The canoe is normal to the water while it is being pulled. The rope is hauled in at a constant ${\displaystyle 5\,{\rm {ft/s}}}$. The dock is ${\displaystyle 5\,{\rm {ft}}}$ above the water. Answer items (a) through (b).

(a) How fast is the boat approaching the dock when ${\displaystyle 13\,{\rm {ft}}}$ of rope are out?

30. A very enthusiastic parent is video taping a runner in your class during a ${\displaystyle 100\,{\rm {m}}}$ race. The parent has the runner center frame and is recording ${\displaystyle 2\,{\rm {m}}}$ from the straight-line track. The runner in your class is running at a constant ${\displaystyle 4\,{\rm {m/s}}}$. What is the rate of change of the shooting angle if the runner passes the parent half a second after the parent's direct shot (after the point in which the runner's motion and the parent's line of sight are perpendicular)?

For each of the following, graph a function that abides by the provided characteristics

30. ${\displaystyle f(1)=f(-2)=0,\ \lim _{x\to \infty }f(x)=\lim _{x\to -\infty }f(x)=0,\ {\mbox{ vertical asymptote at }}x=-3,\ f'(x)>0{\mbox{ on }}(0,2),}$ ${\displaystyle f'(x)<0{\mbox{ on }}(-\infty ,-3)\cup (-3,0)\cup (2,\infty ),\ f''(x)>0{\mbox{ on }}(-3,1)\cup (3,\infty ),\ f''(x)<0{\mbox{ on }}(-\infty ,-3)\cup (1,3).}$

31. ${\displaystyle f{\mbox{ has domain }}[-1,1],\ f(-1)=-1,\ f(-{\tfrac {1}{2}})=-2,\ f'(-{\tfrac {1}{2}})=0,\ f''(x)>0{\mbox{ on }}(-1,1)}$

By assumption, for these problems, assume ${\displaystyle \pi \approx 3.14}$ and ${\displaystyle e\approx 2.718}$ unless stated otherwise. One may use a calculator or design a computer program, but one must indicate the method and reasoning behind every step where necessary.

35. Approximate ${\displaystyle \sin(3)}$ using whatever method. If you use Newton's or Euler's method, do it in a maximum of THREE (3) iterations.

36. Approximate ${\displaystyle {\sqrt {2}}}$ using whatever method. If you use Newton's or Euler's method, do it in a maximum of THREE (3) iterations.

37. Approximate ${\displaystyle \ln(3)}$ using whatever method. If you use Newton's or Euler's method, do it in a maximum of THREE (3) iterations.

45. Consider the differentiable function ${\displaystyle f(x)}$ for all ${\displaystyle x>-2}$ and continuous function ${\displaystyle g(x)}$ below, where ${\displaystyle g(x)}$ is linear for all ${\displaystyle x\geq 1}$ and differentiable for all ${\displaystyle x\in (-2,1)\cup (1,\infty )}$, and ${\displaystyle f(x)}$ and ${\displaystyle g(x)}$ are continuous for all ${\displaystyle x\geq -2}$.

a. Approximate ${\displaystyle f^{\prime }(1.6)}$.

b. Using your answer from (a), find ${\displaystyle \lim _{x\to 1.6}{\frac {f(x)-3}{3-g(x)}}}$.

c. Assume ${\displaystyle f^{\prime }(1.6)=f^{\prime }(2)}$. Find an approximation of the first positive root of ${\displaystyle f(x)}$ shown on the graph. Use only ONE (1) iteration.

d. A computer program found that there exists only one local maximum and minimum on the function ${\displaystyle f(x)}$ and found no local maximum or minimum for ${\displaystyle g(x)}$. Based on this finding, what flaw exists in the program and how can it be fixed?