ANd how do we now a negative times a negative equals a positive? What does that even mean? I tried to think of a story problem or practical application of when we'd need to use this info and I came up with nothing.
2006-12-27 01:49:13 · 10 answers · asked by 0 3 in Science & Mathematics ➔ Mathematics
No. My wife can't think of an everyday application either and she has a PhD in mathematics.
As an abstraction, however, it is vital in the solving of equations, etc. So, indirectly, it is of great use.
2006-12-27 01:57:40 · answer #1 · answered by Matthew H 3 · 0⤊ 0⤋
To some extent a negative number is arbitrary, because we can set "zero" wherever we like - the three temperature scales of Celcius, Fahrenheit, and Kelvin, for example. Negative numbers are very intuitive when used to measure error, variation, and shortfall. Say one meteorologist predicts that today's maximum temperature will be 20 degrees, and another predicts 30, but the actual temperature is 25. The magnitude of each error is the same, but the directions are opposite, so if we couldn't label them positive and negative we couldn't distinguish between them, and the meteorologists wouldn't know in which directions they needed to adjust their models. Many process control systems try to maintain some kind of equilibrium state, and again this is impossible unless the direction of a change can be stated. Similar kinds of assessments are carried out constantly in most process operations to measure conformance to safety, performance and quality targets. Don't stand next to a blast furnace if its operators don't believe in negative numbers.
2006-12-28 04:02:08 · answer #2 · answered by moblet 4 · 0⤊ 0⤋
imagine you're expecting 10 grandkids to show up for a holiday party. you take $20 out of your wallet for each of them. but then, you find out that 2 of them aren't showing up. So, to figure out how much to put back in your wallet you multiply the change in kids (-2) by the loss your wallet suffered for each of them (-$20). The result tells you to put +$40 back into your wallet.
Using negative numbers is all about framing the question. You could imaging using positive numbers instead, but to "formally" state the question, it works just as well to use negatives. And, this confirms intuitively that multiplying neg times neg gets you a positive.
2006-12-27 10:00:31 · answer #3 · answered by crazydiamond399 2 · 2⤊ 0⤋
Your point is correct, but in context, is wrong.
To learn the rest of Algebra (and geometry, trig, calc, and physics, chemistry, etc) you have to use those negative numbers. So, yeah, you can live w/o knowing negative numbers, unless of course you want to build something, or mix chemicals -- you know, live like a modern person?
2006-12-27 09:59:46 · answer #4 · answered by geek49203 6 · 0⤊ 0⤋
You are very discerning. I worked as an engineer for many years and NEVER used negative numbers in any practical kind of way.
2006-12-27 09:52:34 · answer #5 · answered by Dorothy and Toto 5 · 0⤊ 0⤋
Sometimes in computer graphics, I use negative numbers in quaternions to represent orientation, and sometimes these are multiplied together to obtain a new orientation.
So its not impossible, it just tends to be rare.
2006-12-27 09:58:36 · answer #6 · answered by Pfo 7 · 0⤊ 0⤋
If you take the balance of my checking account and multiply it by my net worth, you get the number of years I will serve in debtor's prison.
Merry Christmas! =)
2006-12-27 09:58:56 · answer #7 · answered by Jay E. 3 · 0⤊ 0⤋
most math I learned in school is completly useless. Except for the basics addition, subtraction, multyplying and dividing. Same thing goes for history and english. What a waste.
2006-12-27 09:51:03 · answer #8 · answered by Kimberly B 4 · 0⤊ 2⤋
it is extremely usefull to solve formally some equations
2006-12-27 10:13:38 · answer #9 · answered by gjmb1960 7 · 0⤊ 0⤋
duh...
if i have -7 apples and cindy has -5 apples, how many apples would we have if we multiplied them by eachother?
the answer is simple, 294.5.
2006-12-27 09:52:12 · answer #10 · answered by Anonymous · 0⤊ 1⤋