Geogebra Help

bobbym · 2014-03-31 11:48:09

Yes, there are a lot of ways to come at this problem analytically but that will not always be the case. That is when we separate the heavyweights from the lightweights, when geogebra will shine.

phrontister · 2014-04-01 02:14:19

Hi Bobby,

I used G (only) as my 'go to' prog for this and used its great abilities to quickly give a solution, but I also got some satisfaction in being able to find that alternative (I'd thought I wouldn't find one), which I did with trig and M and needed much more thinking time.

If you're there, I'm here, ready to continue from where we left off...but I'll need to go to bed soon-ish.

bobbym · 2014-04-01 02:15:06

Okay, you want to know what we mean for the curve?

phrontister · 2014-04-01 02:17:11

Yes please...I'm clueless. That was never covered in 4th-year high.

bobbym · 2014-04-01 02:18:34

Did they cover graphing a line and such?

phrontister · 2014-04-01 02:21:04

Not that I recall, but then I wasn't terribly attentive in class and my main aim was to drop out of school that year.

bobbym · 2014-04-01 02:24:26

Without the jargon an equation is a thing where there are variables ( x, y, z, a... etc ) that are linked together by an equal sign.

x^2 + 5x + 2 = 0 is an equation. E=mc^2 is an equation, y = 16t^2 is an equation. x + y is not. Savvy?

phrontister · 2014-04-01 02:29:01

Savvy, kemo sabe.

bobbym · 2014-04-01 02:31:35

Sometimes an equation has only one variable and we must try to solve for it and sometimes it has more than one.

x - 5 = 0 is an equation with one variable. y = 3x - 8 is an equation with 2 variables. If you follow up to here we need to sort of define one term here...

phrontister · 2014-04-01 02:36:24

Yes, I saw the multi-variable conic equations and didn't know what to do with them. I've used 'simultaneous equations' to eliminate variables...

bobbym · 2014-04-01 02:40:35

When we say solve an equation we mean find the value of the variables that make the equation true.

x + 3 = 9

If we say that x = 6 then

6 + 3 = 9 is true so 6 is a solution to that equation. 5 or anything else is not.

phrontister · 2014-04-01 02:42:14

Understood...

bobbym · 2014-04-01 02:46:10

Sometimes an equation can have more than one solution! For instance y = 3x + 9, x = 1 and y = 12 is a solution because 12 = 3 + 9. x = 2 and y = 15 is a solution because 15 = 3(2) + 9. Savvy?

phrontister · 2014-04-01 02:48:27

Yes, no probs with that.

bobbym · 2014-04-01 02:53:19

Notice how each solution can be paired together to form what they call an ordered pair. How amazing.

We can get a lot of them (3,12), (6,15), (9,18)...

By the way they are called ordered pairs because they are a pair where the order counts, (6,12) is not the same as (12,6)

phrontister · 2014-04-01 02:57:19

I think I may have heard that term, but I didn't know what it meant.

bobbym · 2014-04-01 03:01:08

Now each one of those ordered pairs can be plotted on a piece of paper where y ( the second number) and x ( the first number ) are the vertical and horizontal axis. In geogebra enter ( 6 , 9 ).

phrontister · 2014-04-01 03:04:11

Done. I've done that before with, eg, A = ( 6, 9 ).

Last edited by phrontister (2014-04-01 03:07:53)

bobbym · 2014-04-01 03:09:04

Each ordered pair ( solution to the equation ) can be plotted just like that.

phrontister · 2014-04-01 03:12:37

Yes...tried it.

bobbym · 2014-04-01 03:15:00

If you draw a line through all 3 points then geogebra will give you a surprise.

phrontister · 2014-04-01 03:22:13

Hang on...I've lost track. What is the equation we're working on? Is it the one in post #63: y = 3x + 9?

bobbym · 2014-04-01 03:24:42

That is very good, I changed in the middle of this.

Let me get back on track, let's use the equation:

y = 3x + 9 and the 3 ordered pairs (1,12), (2,15), (3,18)

What do those 3 ordered pairs represent?

phrontister · 2014-04-01 03:27:15

I'd anticipated that and entered the coordinates into G...which gave a straight line connecting the lot.

Oops. Sorry, but I didn't answer your Q. They're coordinates.

Last edited by phrontister (2014-04-01 03:30:43)

bobbym · 2014-04-01 03:31:19

Look at the algebra pane and under Line, what is there?

Math Is Fun Forum

#51 2014-03-31 11:48:09

Re: Geogebra Help

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