Mathematical+Reflections,+p+82+0910

A. B 7 May 2010

Big Idea: Negative numbers help us to model many real word situations.

Essential Question: How do I use coordinate grids?

Q: Question A: Answer

Mathematical Reflections #5


 * Q1. How can you tell which quadrant point will fall in by looking at its coordinates?**

A1: If the X value is positive and the Y value is negative, then the point will be in quadrant one. If X is positive but Y is negative, then the point will fall in quadrant two. If X is negative and Y is negative, it will be in quadrant three. Finally, if X is negative and Y is positive, then the point will be in quadrant 4.


 * Q2. You have looked at several problem situations in which you figured out how to make a table of data. You also learned that if you can write an equation to describe how the variables are related, you can use a graphing calculator to graph the equation. How do you figure out what part of the entire graph actually makes sense in the real problem situation? Use an example to help explain.**

A2: For problems such as Jean’s, it would probably make most sense to look at quadrants four and one. This is because she wants to figure out how much profit she will make from her business. Because her starting money was -$800 and she didn’t made any tune-ups yet, so Y would be -800 and X would be 0. It’s not possible do less than 0 tune-ups, so quadrants three and two is not be needed. So quadrant one and four would make the most sense on this real live situation. A3: In this investigation, I extended the coordinate grid to include points with negative coordinates, and I used your graphing calculator to explore graphs of equations. In the graphing calculator I used the WINDOW and ZOOM functions to view the whole of the graphs where the results were not visible. I learned how to get the useful data from the grid by using these two functions to view the specific part of the graph.
 * Q3. Summary **