I need help with interval notation?

(-{infinity sign},3]

if it equals use []

if it doesnt use ()

infinity can never equal a set value so for infinity use ()

Graph Interval Notation

(- <infinity symbol>,3]

You can graph by drawing a solid (not hashed) vertical line going through 3 on the x-axis, then shade the left side of the graph where the origin (0,0) is located.

Or you can use a number line and draw either a ] or a solid dot at 3 and then shade the number line going to the left.

Here is a link to interval notation I quickly found on Google if you wish more study: http://cnx.org/content/m13596/latest/

Interval notation

( and ) means up to (or down to) but not included

[ and ] means up to (or down to) and included

Positive and negative infinity can not be included since you can never get to them The are represented by a sideways 8.

Since your inequality says x is less than or equal to 3 then (-infinity, 3]