Assessment Problem:

The two graphs at right are y= x^2 - kx and y=3. Use the information given to solve the following equations for x.

x^2 -kx = 3

x^2 - kx = 0

Mathematical Issues:

In spite of substantial emphasis on viewing functions via multiple representations, students tend to have a favorite representation they revert to whenever possible. They often do not see the different representations of a function as carrying the same information and simply highlighting certain parts of it differently (e.g., x-intercepts).

Common Responses:

Many students could not see how the graphs could help. Instead, students often attempted to solve the equation algebraically even though the given information is graphical.

Domain:

Patterns & Functions

Theme:

Multiple Representations

Research References:

Gray, R., & Thomas, M. (2001). Quadratic Equation Representations and Graphic Calculators: Procedural and Conceptual Interactions. Paper presented at the 24th Annual Mathematics Education Research Group of Australasia Conference, Sydney, Australia.