To express all real numbers in set notation, you can use the symbol for the set of real numbers, which is denoted by ℝ. Therefore, all real numbers can be written as:
ℝ = {x | x is a real number}
In this notation, the vertical bar | can be read as ‘such that.’ This means the set ℝ contains all values of x that are real numbers. The set of real numbers includes all rational numbers (like integers and fractions) and irrational numbers (like the square root of 2 or pi).