Areas, Accumulations,
& Antiderivatives

  1. For each of the following functions, write down the formula for an antiderivative of that function. Note you can always check your antiderivative by taking its derivative.
    \( a'(x) = 124x^{123}\)
    \( b'(x) = x^{421}\)
    \( c'(x) = x^4+x^3+x^2+x+1 \)
    \( d'(x) = \left(1-x^6\right)^2\)
    \( f'(x) = 2\sqrt[3]{x} + \frac{3}{x^6} \)
    \( g'(x) = \frac{1}{\sqrt[3]{x}} \)
    \( h'(x) = \cos(x)\)
    \( j'(x) = \sin(x) + 1\)
    \( k'(x) = 4\sec(x)\tan(x)\)
    \( m'(x) = \csc^2(x)\)
    \( n'(x) = 3\cos\!\left(3x\right)\)
    \( p'(x) = 2x\cos\!\left(x^2\right)\)
  2. We denote the \(n^\text{th}\) derivative of a function \(f\) as \(f^{(n)}.\) For example, \(f^{(13)}(x)\) is the thirteenth derivative of \(f.\) Given \({f^{(5)}(x) = 12x+1}\) write down a possible formula for \(f(x).\)

  3. Express each of the following sums in (\(\Sigma\)) notation.
    \(2 + 4 + 6 + 8 + 10 + 12\)
    \(1 + 3 + 5 + 7\)
    \(\frac{2}{3}+\frac{4}{9}+\frac{8}{27}+\frac{16}{81}\)
    \(6 - 7 + 8 - 9 + 10 - 11 + 12\)
    \(1 + 4 + 9 + 16 + \dotsb + 529\)
    \(\frac{\sqrt{3}}{2}+\frac{1}{2}+0-\frac{1}{2}-\frac{\sqrt{3}}{2}-1-\frac{\sqrt{3}}{2}-\frac{1}{2}-0+\frac{1}{2}+\frac{\sqrt{3}}{2}+1\)
  4. Calculate the exact value of each of these sums.
    \( \displaystyle \sum_{n=1}^{4} \frac{1}{n} \)
    \( \displaystyle \sum_{n=0}^{5} \frac{2}{3}n \)
    \( \displaystyle \sum_{n=1}^{9} (-1)^n \)
    \( \displaystyle \sum_{n=1}^{1234} 2 \)
    \( \displaystyle \sum_{n=-9}^{10} n^3 \)
  5. Consider the sum \[\sum_{n=1}^{M} \frac{1}{2^n}\;\;=\;\; \frac{1}{2}+\frac{1}{4}+\frac{1}{8}+\dotsb+\frac{1}{2^M} \] where the upper-limit is some variable \(M.\) Calculate the value of this sum for \(M=3\), and for \(M=7.\) What value do you suppose this sum approaches as \(M\) approaches \(\infty?\)
  6. A cyclist is wearing a heart rate monitor while competing in a \(50\) mile bike race. They check the monitor, which tracks their heart rate measured in beats-per-minute (bpm), irregularly throughout the race.
    Minutes since Start 0 10 33 58 70 101 120
    Heart Rate 66 73 80 88 97 68 87
    First, briskly sketch a scatter plot of this data with your independent variable \(x\) measured in minutes since the beginning of the race.
    1. Estimating, how many times did their heart beat in those first \(10\) minutes of the race? What about the first \(33\) minutes of the race? What about the first \(60\) minutes of the race?
    2. Assume that, for the period between any two times that the cyclist checks their heart rate, their heart rate is between the rates the monitor reports. (E.g. between minutes \(58\) and \(70,\) their heart rate stays between \(88\) bpm and \(97\) bpm.) Under this assumption, can you come up with an upper-bound for the number of times their heart beat during the race? I.e. can you find a number \(M\) and say for certain their heart beat no more than \(M\) times during the race? What about a lower-bound?
    3. Now let’s assume something stronger: assume that, for the period between any two times that the cyclist checks their heart rate, their heart rate can be accurately described by a linear function of time. (E.g. for any \(t\) between minutes \(58\) and \(70,\) their heart rate is given by the expression \(\frac{9}{12}(t-58)+58.\)) Now since we are assuming we know their heart rate at any time throughout the race, we should be able to determine a exact number for the number of times their heart beat. How do we determine this number?

Challenges

  1. Recall the classic proof that \( 1+2+3+4+\dotsb+n = \frac{1}{2}n(n+1)\,. \)

    Using a similar “number arrangement” argument, prove that \[ 1^2+2^2+3^2+4^2+\dotsb+n^2 = \frac{n(n+1)(2n+1)}{6}\,. \]