The set of all real roots of the equation x ^ 2-2 = 0 The set of all real roots of the procedure x ^ 2-2 = 0 Let the real root of the equation x ^ 2-2 = 0 be x and satisfy the condition x ^ 2-2 = 0. Therefore, it is expressed as a = {x ∈ R I x ^ 2-2 = 0} What do you mean "and satisfy the condition x ^ 2-2 = 0"? Can r use other common number sets, such as Q or Z

The set of all real roots of the equation x ^ 2-2 = 0 The set of all real roots of the procedure x ^ 2-2 = 0 Let the real root of the equation x ^ 2-2 = 0 be x and satisfy the condition x ^ 2-2 = 0. Therefore, it is expressed as a = {x ∈ R I x ^ 2-2 = 0} What do you mean "and satisfy the condition x ^ 2-2 = 0"? Can r use other common number sets, such as Q or Z

And satisfying the condition x ^ 2-2 = 0 means that the unknown x is the root of the equation x ^ 2-2 = 0 besides the real number r
R is a real number, usually not written
Q stands for rational number
Z is an integer