given the system of equations y=x^2-4x x=4 the number of points of intersection is
y = x² - 4x x = 4
. . . I think this means when the lines cross. So the answer is 1 I think.
When x=4 . . . y = 4^2 - 4*4 = 0
Since y = x² - 4x is a parabola, it only ever crosses any x coordinate once. I think I'm making sense at least.
I didn't know that could be graphed in GeoGebra !
I use the download version - you seem to be using the online version, I wonder if it makes a difference?
Where did you go to graph the equations? I mean how did you do it?
Oh - Sorry Zac, yes, your answer makes perfect sence :)
Melody, You use the "Input" line below the graph. Just type in y=x^2-4*x and press Enter. Similarly for x=4.
Thanks Alan, I had never seen that input bar before
Anyway now, thanks to you and Zac, I have another cool tool!
Do you know if you can put restrictions on the domain or range?
like can I graph y=x^2 for -3<x<2 ?
Yeah....thanks, Alan........I always wondered how to generate a graph in GeoGebra.......!!!!
You can put limits on as follows. In the Input bar type: If(-3<x<2,x^2,NaN)
This results in:
(I changed the colour myself - the default is black).
I should note:
1. The If statement is in the form If(condition, result if condition is true, result if condition is false);
2. NaN stands for Not A Number.
See my edit above.
NaN (Not A Number) is commonly used in many computer languages to represent an undefined region of a function.
Thanks Alan, that is really neat. I mean the true false condition. I like that