Barnett Cover Precalculus Functions and Graphs 4/e   Barnett/Ziegler/Byleen
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Chapter 8: Systems of Equations and Inequalities

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Chapter 8: Systems of Equations and Inequalities


Below are exercises with links to other web sites. When clicking on any of these links a new browser window will open.

    
precalccover.gif (29034 bytes)
minibar2.gif (534 bytes) Exercise 1:
After you've toiled over solving systems of three equations and three unknowns by hand, we'll bet you're ready for some instant answers! Go check out this Linear Equations Solver that will solve these systems in the blink of an eye. Each equation is to be entered in the form:

ax + by + cz = d

The blanks are set up so that you enter the values for a, b, c and d. Your mission is to use this site to help you find two systems that are dependent and two systems that have no solution. (For the latter, the site will say "NULL" -- this is just another way of saying that the solution set is empty.)

minibar2.gif (534 bytes) Exercise 2:
Finding solutions using Gauss-Jordan Elimination is a lot of hard work, isn't it? (Even though it *is* a lot of fun!) This process is really intended for solving really large systems of equations with lots of unknowns via computers. Would you want to solve this by hand?
0.7v + 5/8w - 78x + 345.7y - z = 23
1/2v - 89w + 89/7x + 42.375y + 10z = 7
3v + 7w - 4x + 18y        = 0
45v - 4.32w + 8/77x - 22y + 5.4z = -2
9v + 9w + 9x + 9y + 9z = 8

Go to The Java Matrix Solver and solve this system. Be sure to read through their example and instructions. Just put a blank space between the entries of each row and hit ENTER (on your keyboard) between the rows. The site only gives decimal solutions... But, if we were figuring out how much rocket fuel to use, 3.14159 gallons would be just as good as pi gallons.

minibar2.gif (534 bytes) Exercise 3:
In section 8-3, you learned about solving systems of nonlinear equations. We can see that our solutions are simply the points of intersection between the graphs. The Quadratic Curve Applet will allow you to play with the solutions (intersections) of various lines and parabolas. (In calculus, you will be asked to find the area between these curves and you'll need to be able to find the intersections to accomplish this goal.) You can move the individual graphs by dragging the squares and you can change their shapes by dragging the circles. Be sure that your browser window is maximized so that you can see the information to the right of the graph. Keep a record of your work by writing down your equations and drawing the graphs by hand.
1) Draw a graph that has two distinct solutions.
2) Draw a graph that has only one solution.
3) Draw a graph that has no solutions.
4) Draw a graph that has two distinct solutions with the y coordinates being the same in both. What type of line did you have to draw?
    


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