Use parentheses for endpoints not included: ( (a, b) )
Use brackets for endpoints included: ( [a, b] )
Use a parenthesis on infinity or negative infinity: ( (-infty, b) ), ( (a, infty) )
Combine with brackets and parentheses as needed: ( [a, b) ), ( (a, b] )
Use a union symbol ( cup ) for separate intervals: ( (-infty, 2) cup (5, infty) )
Write all solutions in interval form using the correct endpoint symbols
Use ( emptyset ) for no solution
Use ( (-infty, infty) ) for all real numbers