Question 45435
x^2>=9
x^2-9>0
(x-3)(x+3)>=0
Plot the points 3 and -3 on a number line thus breaking 
the number line into three intervals:
x<-3
-3<x<3
3<x
Check a value in each interval to determine whether the 
interval values are or are not part of the solution, for
example:
In the interval -3<x<3 pick the value x=0
Then check 0^2>=9
0>=9
This is false so that interval conains no solutions.
Then check a value in each of the other two intervals.

Cheers,
Stan H.