How do I demonstrate an algebraic equation on a "number line"? For example, how do I show X<6 on a "number line"?
First draw a number line like this:
---------------------------------------------------
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
Since it's " < ", we put an OPEN circle at 6
--------------------------------------o------------
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
(If it were " < ", we'd put a closed circle)
Now since it's LESS THAN, we darken the number line
to the LEFT of 6 and put an arrowhead on the far left
end to show that it continues indefinitely to the
left.
<=====================================o------------
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
That's the graph of x < 6.
Another example:
To draw the graph of x > -3
put a closed circle at -3 like this:
-----------=---------------------------------------
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
It's a closed circle because the inequality
symbol is >
Then since it's GREATER THAN, we darken the number line
to the RIGHT of -3 and put an arrowhead on the far right
end to show that it continues indefinitely to the
right.
-----------========================================>
-6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10
That's the graph of x > -3
Edwin