Math Problems
 

Let's do some Math.

1) Solve the linear system.

{2x + 5y = -2
{3x - 2y = 4


2) Solve the system.

{3x + 4y = -3
{2x + y = 8

I see a joke somewhere in here......

Okay, I have the answer for the first one... but what's the point? Unless there's a punchline, we're just doing high school algebra. And so far, I don't see a punchline...

The punchline is Shorty is going to get the message board to do his homework for him.

I'm trying not to forget math by the time senior year rolls around.

I'm out of school, hater.

Quik, I am getting (2, -1) for this first one, and that is not correct, by checking.. I don't know what I'm doing wrong here.

I'm getting some odd fractions for the first one... I get X=16/19 and Y=-14/19. If this is supposed to have an elegant solution, I don't see it.

just pulled it from some old tests, looking at the ones i got wrong, this was one of them Not sure if an 'elegant solution' is the real solution or not.

Bah ! Too complicated for me.

Shorty has been defined.

I have reached the conclusion that I will never be good at math. I just checked both problems, and both of my solutions are wrong. Grrr. Maybe I just shouldn't take math senior year (only 3 years are required).

You and I cannot possibly be related.

:)

If I wanted to do this via matrices and row reduction, I could. But I cheat. I use Maple.

Prob 1: X = 16/19, Y = -14/19.

Prob 2: X = 7, Y = 6

I'm really thinking about doing that... If I did, I would take three science classes, Physics, Advanced Biology(you get to clone shit in this class), and advanced chemisty

Maple?

Take math your senior year (assuming you plan to go to a 4-year college). It doesn't matter whether or not you're good at it - just do it.

Maple is a rather advanced computer math/engineering-type program used lots in colleges and universities.

I'll try and type out the work for the 2nd one (since it has easier numbers)...


2x + y = 8

y = 8 - 2x

3x + 4y = -3

3x + 4*(8 - 2x) = -3

3x + 32 - 8x = -3

32 - 5x = -3

-5x = -35

x = 7

2x + y = 8

2*(7) + y = 8

14 + y = 8

y = 6

(7,6)

Just do the same thing for the first one, though it'll take longer with those ugly numbers.

This is quite possibly the easiest math I've ever done.

I'll show #1, just to give you an idea

2x + 5y = -2
2x = -2 - 5y
x = -1 - (5/2)y

3x - 2y = 4
3(-1 - (5/2)y) - 2y = 4
-3 - (15/2)y - (4/2)y = 4
-3 - (19/2)y = 4
-(19/2)y = 7
y = -(2/19)*7
y = -(14/19)

2x + 5(-14/19) = -2
2x + (-70/19) = -(38/19)
2x = (32/19)
x = (1/2)*(32/19)
x = 16/19

x = 16/19
y = -14/19

oh, i was thinking graph

I'd taken 4 years of math after my junior year and being my pre calculus teacher taught me nothing (his method of teaching was yelling at students when they didn't know something) I didn't take math my senior year. Of course, when I get to college I'm going to be taking Precalc 2 and microeconomics, my first semester with calculus and macroeconomics my second, and I have to have around a 3.8 to transfer into the school I want to be in at the university I'm attending.

I hate math... :(

Hello, math genius people...

The answer to #2 is NOT (7,6)

It is (7, -6)

I must have learned a different way of solving this (or maybe this is what TredWel means by matrices & row reduction)....

1) Solve the system.
2x + 5y = -2
3x - 2y = 4

or,

6x + 15y = -6
-6x + 4y = -8
---------------------
19y = -14
y = -14/19

3x - 2(-14/19) = 4
57x + 28 = 76
57x = 48
x = 48/57 = 16/19

2) Solve the system.

3x + 4y = -3
2x + y = 8

or
3x + 4y = -3
-8x - 4y = -32
--------------------
-5x = -35
x = 7

14 + y = 8
y = 8 - 14
y = -6

Now now... I'm smart, but no need to flatter me.

You're not going to need calc in either of those economics classes. Or at least, I didn't.

And as long as you have no plans beyond your freshman year in college, you're all set. Skip math, definitely. Go with something easier - it will definitely pay off in the end.

Shorty's new avatar:

peee-yew

do i smell sarcasm?

Wrong, asshole.

I don't spell words incorrectly.

But other than that, nice job. :D

:)

No, but I'll need the class for my transfer.

I hate to say this being a math teacher, but I will have to side with Shorty on this one. There is reason for future mathematicians, engineers, etc to have to know how to do this. But for anyone who will not have to use extensive math in their career, there is no reason to waste more than a week on systems of equations. (Graphing calculators and computers will solve any system you throw at them. Especially 2nd and 3rd order systems.) There are so many more richer topics students in algebra I could explore.

Saying that solving system of equations is not the most rewarding thing within the study of algebra (part of mathemtaics) isn't exactly backing up the notion that studying mathematics is worthless.

I think one might be able to argue that the study of mathematics -- even some areas of math that are themselves not particularly practical in direct effect - is useful in and of itself. That the sort of skills one learns in the study of challenging math are useful skills to have, even if one is never called upon to solve a series of equations, or to determine the limit of an infinite series.

Agree 100%. That is why I am floored by teachers who still spend 2 months on their systems of equations units. They start with graphing a line, then teach substitution, then teach combining with addition and subtraction, then with multiplication, then with matrices, and so on. Why not explore matrices and graphs farthur using mordern technology instead of giving kids tests with the same problem over and over (like it looks like Shorty's teacher did)? Every kid at our district's high schools have graphing calculators and most teachers use them about once a year.

Fifty years ago there was some practicality to teaching how to divide 26232 by 191. Now it is not a skill that needs inordinate amounts of time spent on it. I have a math degree, I would not ever do that by hand. Well, graphing calculators can tackle a lot of the "computational" algebra and allow the kids to actually understand why they are studying graphing lines and systems of equations in the first place. (I never learned until my master's degree a practical use for matrices. This includes the honors track of major school district and the mathematics program of a large university. Maybe some teachers need to change their lesson plans every 30 years?)