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Interval Notation

What about those two-piece guys?

number line showing x < 0 or x > 3

The left piece is ( negative infinity, 0 )   The right piece is ( 3 , infinity)

Remember the regular notation:

x < 0 or x > 3 We have to deal with the "or"
 

Remember way back when you learned sets?

"or" means "union" and we use "U"

So, the interval notation is

( negative infinity, 0 ) U ( 3 , infinity)
 

TRY IT:

Write the interval notation for:

        x is less than or equal to -5 or x > 0

x is less than or equal to 3 or x is greater than or equal to 10

      x is less than 0 or x is greater than 2

I'll be using interval notation in the rest of the lessons.