November 2006 | ||||||
Sun | Mon | Tue | Wed | Thu | Fri | Sat |
1 | 2 | 3 | 4 | |||
5 | 6 | 7 | 8 | 9 | 10 | 11 |
12 | 13 | 14 | 15 | 16 | 17 | 18 |
19 | 20 | 21 | 22 | 23 | 24 | 25 |
26 | 27 | 28 | 29 | 30 | ||
Oct Dec |
The Quadratic Formula
What's going on in math these days?
I asked.
Oh, quadratic equations,
he said. You know, b squared minus 4 a c.
You mean the quadratic formula?
I asked.
Yes.
So I had him explain it. And we went thru the derivation, which he got mostly right. And I showed him what it meant graphically. And then I told him what I used to ask on exams.
I told him how I promised my students that they would have to derive the quadratic formula on the test. And I told him how when I wrote the tests, I would tell them that instead of starting from
ax2 + bx + c = 0
that they should derive the formula using different coefficients:
Dx2 + Ex + F = 0.
His eyes widened. And then I pointed out that it that it could be worse: I could have used α/β/γ as the coefficients and ξ as the unknown instead of x.
A few minutes later, him mom arrived. As he got into the car I said, Practice the derivation tonite with D/E/F,
and you'll never have any trouble with it.
Or with ξ!
he said.
What do you think are the odds that he did it?
12:06:44 AM permalink: [] feedback: comments: []