Chapter 42
Homework for the fourteenth week

42.1 Homework

Notes also available as PDF.

Practice is absolutely critical in this class.

Groups are fine, turn in your own work. Homework is due in or before class on Mondays.

• Exercises for 7.3
  • 25, 26, 68, 70
• Exercises for 7.4
  • 64, 65, 66 (note: making a profit implies R - C > 0 where R is the revenue and C is the cost)
• Exercises in 7.5
  • 60, two different ways. First, substitute points into {x}^{2} + {(x + 30)}^{2} - 15{0}^{2} and plot the line segments. Try x \{80,85,90,95,100\}. In this case, you’ll happen to find the answer. For the other way, use the Pythagorean theorm as in the text.
• Exercises in 8.1
  • 56: Use the point formula for a line,

    {x - {x}_{0}\over { x}_{1} - {x}_{0}} = {y - {y}_{0}\over { y}_{1} - {y}_{0}},

    to determine the equation of the closest points to each requested x. Then substitute the x value in the middle and find the y.

• Exercises in 8.3:
  • 70, 72, 74
• Exercises in 8.6:
  • 50
• Exercises in 8.7:
  • Use either substitution or elimination: 50, 78 (yes, I had to assign a “speed of a train leaving\mathop{\mathop{…}}” problem), 86
• Exercises in 8.8:
  • 30, 34

Note that you may email homework. However, I don’t use Microsoft^TM products (e.g. Word), and software packages are notoriously finicky about translating mathematics.

If you’re typing it (which I advise just for practice in whatever tools you use), you likely want to turn in a printout. If you do want to email your submission, please produce a PDF or PostScript document.