Thread: Need help Grade 11 math

the domain of this quadratic relation in my math book is D= {X E R| 2 <_ x <_ 9} and the range is R = {y E R| 1 <_ y <_ 5} but I don't get what the E R means can someone please tell me.

Translation: The domain consists of all x in the set of real numbers such that x is greater than equal to 2 and less than or equal to 9.

means 'belongs to'. refers to the set of all real numbers.