Express set of numbers using interval notation and set-builder notation:
numbers more than 2 units from 8
we were coming up with:
x|610; but my daughter says her teacher said the >< symbols should be going in the same direction??
In order to be more than 2 units away from 8, a number must
be either left of 6 OR right of 10. So the graph is
<============================o-----------o==================>
-3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
In interval notation that is
(-,6) U (10,)
and the set builder notation is:
{x | x < 6 OR x > 10}
But since your teacher says the symbols must go in
the same direction, then we can do either of two
things. We can change the
x < 6
to
6 > x, which is the same thing,
and make it
{x | 6 > x OR x > 10}
or else we can change the
x > 10
to
10 < x, which is the same thing,
and make it
{x | x < 6 OR 10 < x}
But most teachers would not require
both symbols to go the same way.
Edwin