Question

PROBLEM: Solve the inequality \(|2x-5| \leq 11\).

SOLUTION: Here is a short video (less than 5 mins) describing the solution algebraically and graphically. I want to make more like this so any comments/criticisms are very much appreciated. :)

http://youtu.be/IYur2uvz5J0

Answer 1

Can you use GeoGebra to solve this kind of things?

Answer 2

Yes, I show how to do so in the video. :)

Answer 3

one small correction at 1:40 you say "the blue line is 2x-5" when it is actually 5-2x

Answer 4

Basically you type two equations in the "input" bar at the bottom of the geogebra window:

1) y = 11
2) y = abs(2x-5)

The solution is wherever the absolute value function (shaped like a "V") lies BELOW the horizontal line y = 11. :)

Answer 5

great... thanks!

btw i think what you are doing is really cool.. doing videos and stuff like that, you sound like a pretty amazing teacher... keep up the good job!

Answer 6

Thank you satellite, I added an annotation to make the correction.

Answer 7

looks good to me

Answer 8

the only thing i would add, because usually people miss this part, is that solving for example
\[|2x-5| \leq 11\] is not just solving that inequality but all all others as well.

Answer 9

meaning that once you have solved
\[|2x-5|\leq 11\] you also have solved
\[|2x-5| > 11\]
\[|2x-5|\geq 11\]
\[|2x-5|<11\]

Answer 10

but maybe that is a topic for another video

Answer 11

What do you mean by "you have also sloved?"

0 is a solution of \(|2x-5|\leq 11\) because |2*0-5| = 5 , which is less than or equal to 11.

But 0 is not a solution to \(|2x-5| \geq 11\) because |2*0 -5|=5 which is NOT greater than or equal to 11. :(