Especially for Mo and Becky's students

IRS Form QF (also in pdf), courtesy of Dan Velleman.

Who Can Use Form QF?
You can use Form QF if all of the following apply.

• You need to solve an equation of the form Ax² + Bx + C = 0.
• A is not equal to zero.

Oh, wait, I forgot. Mo's students are Canadian. This won't work for them.

[via Left2Right]

Comments

[Moebius Stripper]

Heh, seems fitting. Last term I made the mistake of pointing out that you couldn't use the quadratic formula if there was no x^2 term. This led to one student defending her test answer that there was no solution to the equation 2x-8=0: "there's no x^2!"

Yes, this is college.

[Leon]

Being a math teacher myself, I appreciate the sentiment of this post.

So after an entire semester or two of algebra, most students can manipulate the statements at some superficial level. But I don't think the majority of students really understand what a variables and expressions and equations are, and the difference between them.

As funny as the IRS quadratic formula is, I'm wonder if it could be adapted to teach remedial algebra... starting out with the expression associated with each line written out to the right, and making them go through numerical examples, and then at more advanced levels, making them actually work through a worksheet symbolically to determine the expression it computes.

Then you could also have different forms that compute equivalent expressions, and explain that these two forms always arrive at the same expression. This might particularly useful to explain associativity, which seems to give students the most trouble of all the basic algebraic laws.

Though, working through the form symbolically, I had problems coming up with the right discriminant. I found it difficult to distinguish between a line number and a literal number. I'd recommend either labelling lines with letters and/or writing "multiply line 1 by the number 2" instead of "multiply line 1 by 2" which threw me for a while.