The Trig Explorer/The Trig Explorer.iso/pc/2xy_demo/examples/graphs/nline1.xmp

Text File | 2000-03-31 | 3.1 KB | 221 lines

>4.Marking sets on the number line
xŒ[-2;4)Ÿx≥2
MYSZEK 2xy
EXAMPLE
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BLURB
1`We are going to show the solution of the inequalities:
1`#@xŒ[-2;4)Ÿx≥2@
1`on the number line. To do that we open the &Marking sets& window.
2`Following this hint, we write the inequalities in the window.
3`We open the panel with logical symbols
4`We used the on-screen keyboard to write the connective $"Ÿ"$.
4`Instead, we could have typed &AND& using the keyboard.
5`Having introduced the inequalities, we press &ENTER&.
6`Now we should mark the conditions on the number line.
6`Look at the panel below the title of the window.
7`We click on an inequality or interval to select it.
7`Let us start from the interval: $"xŒ[-2;4)"$
21`Now we should mark the interval on the number line.
21`#"Notice carefully, how to do it!"
8`To mark the interval we place the mouse at the point
8`#$"x=-2"$,
8`#press the left mouse button...
28`#drag to the point
28`#$"x=4"$.
28`#and release the button.
9`Next we should mark which end-points belong to the interval.
9`Our closed interval contains its left-hand end-point, so we click
9`the mouse at $"x=-2"$ to mark the left end of the interval.
10`At last we press &ENTER&.
11`Now we select the inequality:`#$"x≥2"$
12`To mark the condition we drag the mouse from
12`$"x=2"$ to the right edge of the window.
13`Next we mark the point $"x=2"$, since this
13`value of $"x"$ satisfies our weak inequality.
14`Now we should mark all the points and intervals
14`that satisfy &both& conditions together.
15`We click the mouse button on the bar
15`above the number line at $"x=2"$...
25`and between $"2"$ and $"4"$.
16`We press &ENTER& to check our work.
17`It is possible to rewrite the conditions as a single interval:
17`#$"xŒ[2;4)"$
17`We press &ENTER& to write the inequalities in another form.
18`Having introduced the new version of the conditions,
18`we press &ENTER& again. The program checks our calculations.
20`We use the semicolon   $";"$
20`to separate the ends of an interval
100`#We show how to use 2xy
100`#to mark sets on the number line.
100``#"The presentation proceeds automatically."`
101`#In a moment &Examples& window will appear.
101`You can watch the same presentation again,
101`#or load the next example,
101`#or close the window and solve your own problem.
102`The information about what to do now is
102`displayed below the title of the window