by Justice Wed Sep 15, 2010 7:02 pm
x^2-2x>0
x(x-2)>0
Break it into intervals (-∞,0)∪(0,2)∪(2,∞+)
and you pick a number from each interval to check which satisfy it.
so.....
Pick -10 for the first interval
(-10)(-10-2)>0
true! thus we know (-∞,0) is one interval
Pick 1 for(0,2)
(1)(1-2)>0
false!
thus we know (0,2) is not one interval
pick 100 for the final interval
(100)(100-2)>0 true!
Thus the answer is (-∞,0]∪[2,∞+)
[ means inclusive and ( means exclusive
If you have any questions post