Wednesday, February 6, 2013


This type of coordinate problem is occurring more frequently. Students need exposure to these...

The graph of the quadratic function f(x) = bx^2 + ax + c intersects the x-axis at 3 and 4 and the y-axis at 5.
b = ?

Answer: 5/12


1.  What in the question do you think  might cause students to struggle?
2. Do you use a standard approach to these types of coordinate problems, e.g., an x-y table?
3.  Do you usually discuss at least 2 methods for these? You know how I feel!

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Joshua Zucker said...

3,4,5 given in the problem sounds so Pythagorean, and then the answer is 5/12 which also sounds Pythagorean. I want my students to wonder if this is a coincidence or not!

Dave Marain said...

I've missed your divergent thinking, Joshua!Even though the "12" is just 3•4, it is coincidental that I chose the "5". Or I'm just perverse enough to choose 3-4-5!

Speaking of connections, 12/5 is the alt on the hyp of a 3-4-5 triangle!

I know that my capacity to sustain these posts is limited at this point, but you've reminded me why I started! Nice to hear from you and I hope you're healthy and happy.

So, do you agree with me that the impact of SAT's would be lessened if textbook publishers included these types of questions as routine homework exercises without qualifying them as standardized test problems?