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Section 2.2 : The Limit

  1. For the function \(\displaystyle f\left( x \right) = \frac{{8 - {x^3}}}{{{x^2} - 4}}\) answer each of the following questions.
    1. Evaluate the function at the following values of \(x\) compute (accurate to at least 8 decimal places).
      1. 2.5
      2. 2.1
      3. 2.01
      4. 2.001
      5. 2.0001
      1. 1.5
      2. 1.9
      3. 1.99
      4. 1.999
      5. 1.9999
    2. Use the information from (a) to estimate the value of \(\displaystyle \mathop {\lim }\limits_{x \to 2} \frac{{8 - {x^3}}}{{{x^2} - 4}}\).
    Solution
  2. For the function \(\displaystyle R\left( t \right) = \frac{{2 - \sqrt {{t^2} + 3} }}{{t + 1}}\) answer each of the following questions.
    1. Evaluate the function at the following values of \(t\) compute (accurate to at least 8 decimal places).
      1. -0.5
      2. -0.9
      3. -0.99
      4. -0.999
      5. -0.9999
      1. -1.5
      2. -1.1
      3. -1.01
      4. -1.001
      5. -1.0001
    2. Use the information from (a) to estimate the value of \(\displaystyle \mathop {\lim }\limits_{t \to \, - 1} \frac{{2 - \sqrt {{t^2} + 3} }}{{t + 1}}\).
    Solution
  3. For the function \(\displaystyle g\left( \theta\right) = \frac{{\sin \left( {7\theta } \right)}}{\theta }\) answer each of the following questions.
    1. Evaluate the function at the following values of \(\theta \) compute (accurate to at least 8 decimal places). Make sure your calculator is set to radians for the computations.
      1. 0.5
      2. 0.1
      3. 0.01
      4. 0.001
      5. 0.0001
      1. -0.5
      2. -0.1
      3. -0.01
      4. -0.001
      5. -0.0001
    2. Use the information from (a) to estimate the value of \(\displaystyle \mathop {\lim }\limits_{\theta\to \,0} \frac{{\sin \left( {7\theta } \right)}}{\theta }\).
    Solution
  4. Below is the graph of \(f\left( x \right)\). For each of the given points determine the value of \(f\left( a \right)\) and \(\mathop {\lim }\limits_{x \to a} f\left( x \right)\). If any of the quantities do not exist clearly explain why.
    1. \(a = - 3\)
    2. \(a = - 1\)
    3. \(a = 2\)
    4. \(a = 4\)
    Solution
    The graph of a function on \(-5 \le x \le 5\) made up of three pieces.  The first piece starts at (-5,1) and rises to a closed dot at (-3,4).  The second piece starts at an open dot at (-3,-2), rises through an open dot at (-1,1) to a peak of about 1.7 near \(x = 0.5\) and then falls to an open dot at (2,1).  There is also a closed dot at (-1,3) above the open dot at \(x = -1\).  The third piece starts at the same open dot at (2,1), rises steeply to a peak at a closed dot at (4,5) and then falls to (5,3).
  5. Below is the graph of \(f\left( x \right)\). For each of the given points determine the value of \(f\left( a \right)\) and \(\mathop {\lim }\limits_{x \to a} f\left( x \right)\). If any of the quantities do not exist clearly explain why.
    1. \(a = - 8\)
    2. \(a = - 2\)
    3. \(a = 6\)
    4. \(a = 10\)
    Solution
    The graph of a function on \(-12 \le x \le 12\) made up of three pieces.  The first piece starts at (-12,4), falls to its lowest point at an open dot at (-8,-6) and then rises to a closed dot at (-2,3).  There is also a closed dot at (-8,-3) above the open dot at \(x = -8\).  The second piece comes down from positive infinity just to the right of \(x = -2\), reaches a low point of about 1 near \(x = 0\), rises to about 3 near \(x = 2.5\), dips slightly and ends at an open dot at (6,2).  The third piece starts at a closed dot at (6,5), rises to a peak of about 5.5 near \(x = 7\) and then falls through a closed dot at (10,0) to about -4 at \(x = 12\).
  6. Below is the graph of \(f\left( x \right)\). For each of the given points determine the value of \(f\left( a \right)\) and \(\mathop {\lim }\limits_{x \to a} f\left( x \right)\). If any of the quantities do not exist clearly explain why.
    1. \(a = - 2\)
    2. \(a = - 1\)
    3. \(a = 1\)
    4. \(a = 3\)
    Solution
    The graph of a function on \(-4 \le x \le 4\) with a vertical asymptote at \(x = -2\).  To the left of the asymptote the graph starts at about (-4,1.5) and increases toward positive infinity as it approaches \(x = -2\).  To the right of the asymptote the graph comes up from negative infinity and rises to an open dot at (-1,1).  There is a closed dot at (-1,3) above the open dot at \(x = -1\).  From the open dot at (-1,1) the graph falls to its lowest point at an open dot at (1,-3), then rises through a closed dot at (3,4) and continues upward.