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2.9: Extra Problems for Chapter 2

  • Page ID
    155809
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    1. Find the derivative of \(f(x) = 4x^{3} - 2x + 1\).
    2. Find the derivative of \(f(t) = 1/\sqrt{2t - 3}\).
    3. Find the slope of the curve \(y = x(2x + 4)\) at the point \((1, 6)\).
    4. A particle moves according to the equation \(y = 1/(t^{2} - 4)\). Find the velocity as a function of \(t\).
    5. Given \(y = 1/x^{3}\), express \(\Delta y\) and \(dy\) as functions of \(\Delta x\) and \(dx\).
    6. Given \(y = 1/\sqrt{x}\), express \(\Delta y\) and \(dy\) as functions of \(\Delta x\) and \(dx\).
    7. Find \(d(x^{2} + 1/x^{2})\).
    8. Find \(d(x - 1/x)\).
    9. Find the equation of the line tangent to the curve \(y = 1/(x - 2)\) at the point \((1, -1)\).
    10. Find the equation of the line tangent to the curve \(y = 1 + x \sqrt{x}\) at the point \((1, 2)\).
    11. Find \(dy/dx\) where \(y = -3x^{3} - 5x + 2\).
    12. Find \(dy/dx\) where \(y = (2x - 5)^{-2}\).
    13. Find \(ds/dt\) where \(s = (3t + 4)(t^{2} - 5)\)
    14. Find \(ds/dt\) where \(s = (4t^{2} - 6)^{-1} + (1 - 2t)^{-2}\).
    15. Find \(du/dv\) where \(u = (2v^{2} - 5v + 1)/(v^{3} - 4)\).
    16. Find \(du/dv\) where \(u = (v + (1/v))/(v - (1/v))\).
    17. Find \(dy/dx\) where \(y = x^{1/2} + 4x^{3/2}\).
    18. Find \(dy/dx\) where \(y = (1 + \sqrt{x})^{2}\).
    19. Find \(dy/dx\) where \(y = x^{1/3} - x^{-1/4}\).
    20. Find \(dy/dx\) where \(y = e^{x} \cos^{2} x\).
    21. Find \(dy/dx\) where \(x = \sqrt{y} + y^{2}, \ y > 0\).
    22. Find \(dy/dx\) where \(x = y^{-1/2} + y^{-1}, \ y > 0\).
    23. Find \(dy/dx\) where \(y = \sqrt{1 - 3x}\).
    24. Find \(dy/dx\) where \(y = \sin(2 + \sqrt{x})\).
    25. Find \(dy/dx\) where \(y = u^{-1/2}, \ u = 5x + 4\).
    26. Find \(dy/dx\) where \(y = u^{5}, \ u = 2 - x^{3}\).
    27. Find the slope \(dy/dx\) of the path of a particle moving so that \(y = 3t + \sqrt{t}, \ x = (1/t) - t^{2}\).
    28. Find the slope \(dy/dx\) of the path of a particle moving so that \(y = \sqrt{4t - 5}, \ x = \sqrt{3t + 6}\).
    29. Find \(d^{2}y/dx^{2}\) where \(y = \sqrt{4x - 1}\).
    30. Find \(d^{2}y/dx^{2}\) where \(y = x/(x^{2} + 2)\).
    31. An object moves so that \(s = t \sqrt{t + 3}\). Find the velocity \(v = ds/dt\) and the acceleration \(a = d^{2}s/dt^{2}\).
    32. Find \(dy/dx\) by implicit differentiation when \(x + y + 2x^{2} + 3y^{3} = 2\).
    33. Find \(dy/dx\) by implicit differentiation when \(3xy^{3} + 2x^{3}y = 1\).
    34. Find the slope of the line tangent to the curve \(2x \sqrt{y} - y^{2} = \sqrt{x}\) at \((1, 1)\).
     \(\square\) 35. Find the derivative of \(f(x) = \left|x^{2} - 1\right|\).
      \(\square\) 36. Find the derivative of the function \[f(x) = \begin{cases} 1 &\quad \text{if } x \text{ is an integer}, \\ 0 &\quad \text{otherwise}. \end{cases} \nonumber\]
     \(\square\) 37. Let \(f(x) = (x- c)^{4/3}\). Show that \(f'(x)\) exists for all real \(x\) but that \(f''(c)\) does not exist.
    \(\square\) 38. Let \(n\) be a positive integer and \(c\) a real number. Show that there is a function \(g(x)\) which has an \(n\)th derivative at \(x = c\) but does not have an \((n + 1)\)st derivative at \(x = c\). That is, \(g^{(n)}(c)\) exists but \(g^{(n+ 1)}(c)\) does not.
    \(\square\) 39. (a) Let \(u = |x|, \ y = u^{2}\). Show that at \(x = 0\), \(dy/dx\) exists even though \(du/dx\) does not.
    (b) Let \(u = x^{4}, \ y = |u|\). Show that at \(x = 0\), \(dy/dx\) exists even though \(dy/du\) does not.
    \(\square\) 40. Suppose \(g(x)\) is differentiable at \(x = c\) and \(f(x) = |g(x)|\). Show that
    (a) \(f'(c) = g'(c)\) if \(g(c) > 0\),
    (b) \(f'(c) = -g'(c)\) if \(g(c) < 0\),
    (c) \(f'(c) = 0\) if \(g(c) = 0\) and \(g'(c) = 0\),
    (d) \(f'(c)\) does not exist if \(g(c) = 0\) and \(g'(c) \neq 0\).
    \(\square\) 41. Prove by induction that for every positive integer \(n\), \(n < 2^{n}\).
    \(\square\) 42. Prove by induction that the sum of the first \(n\) odd positive integers is equal to \(n^{2}\), \[1 + 3 + 5 + \cdots + (2n-1) = n^{2}. \nonumber\]

    This page titled 2.9: Extra Problems for Chapter 2 is shared under a CC BY-NC-SA 3.0 license and was authored, remixed, and/or curated by H. Jerome Keisler.

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