Quadratic nightmares

[cjsmith]

How does one solve a quadratic equation quickly? (Without sacrificing accuracy, of course, and without making it more likely that an arithmetic goof will creep in.)

I know how to use the quadratic formula, but I'm slow and methodical. On a test, minutes count. I've been warned that on the upcoming chemistry exam, seconds may count. This one has been announced as "hard" and "if you haven't done all the practice problems three times over, you won't have time to complete the test". It's going to be FULL of this stuff (for equilibrium calculations). I don't have time between now and the test to do all the practice problems three times over, not if I want sleep too.

How do you solve these dang things FAST?

Oooo. Are there calculators that just do this for you, once you've set up the equation? If so, I'd better go get one. If that's what other students have, I'd be a fool to handicap myself.

Comments

[cjsmith.livejournal.com]

That is awesome. I may need one of those.

I turned in the last test with a few seconds to spare. That one was announced as "easy" and "if you've done the practice problems you should have no trouble". Conceptually, I'm fine with all of this material, but it's clear I'm dead slow.

[leback.livejournal.com]

At the time, my calculator was pretty fancy stuff, but I suspect there are cheaper programmable calculators (or ones that have the quadratic formula built in) out there now. Does the instructor have any rules about what kinds of calculators you're allowed to use for the exam? I assume they don't want students carrying things in which they can store all the information they're meant to have memorized, but maybe this isn't that sort of test...

To some extent, having a solid conceptual handle on the stuff can make up for slowness -- if you only finish half of something, but you still get as many problems right as anyone who handed it in early, you probably still get an A. :-)

[cjsmith.livejournal.com]

There are no rules at all limiting the kinds of calculators one can use. This instructor is the kind who gives us constants, too, so storing those in memory isn't an issue. :-)

Sadly, there's no curve on this; if I get 85% on the test, no matter how many concepts I have down cold, I get a B. It's time to get myself one of those calculators, right bloody now.

[leback.livejournal.com]

Okay, the no-curve thing is nuts. I'm sorry, but after the stories you told about your classmates last quarter, I'm pretty confident that, slow and methodical though you may be, you're going to be at or near the top of the class on this exam. So if you get a B, everybody gets a B (or worse) -- which I know doesn't help you any, but says to me the instructor's doing something wrong.

Anyway, good luck finding an appropriate calculator. I see that there are plenty of 99-cent iPhone apps that will solve quadratic equations, so if you don't come across any other reasonably easy and inexpensive option, you're welcome to borrow my phone for the exam. :-)

[cjsmith.livejournal.com]

I honestly don't know why he's making a test he knows we can't complete in the time given. I do know that he's frustrated that many of the students don't seem to be doing the "homework" (practice problems); maybe he's trying to make the point that doing them -- aka Listening To The Teacher, Thank You -- will help. If that's it, then I really wish he'd chosen another way to make his point. I am doing the work and I'm not pleased to have to face this kind of hurdle just because others aren't listening.

[lizzie-omalley.livejournal.com]

One of the people at the high school I teach at was a doctor in a "former life" and is now teaching a night class at the local Jr. college as well as high school. He was lamenting the other day that the students don't read so they can't keep up with his lectures. I am thinking it's a universal problem in the US these days.

[cjsmith.livejournal.com]

Given what I see around me, I suspect that's right. There are students in my classes who listen, who do the work, and who are doing very well. They're rare. If I were a teacher I'd be at my wits' end with most of the class.