we know that
The standard form of set-builder notation is
“x satisfies a condition”
This set-builder notation can be read as “the set of all x such that x (satisfies the condition)”.
In this problem, there are 2 conditions that must be satisfied:
1st: x must be a real number
In the notation, this is written as “x ε R”.
Where ε means that x is “a member of” and R means “Real number”
2nd: x is greater than or equal to 1
This is written as “x ≥ 1”
therefore
Combining the 2 conditions into the set-builder notation:
X = x
the answer is
X = x ε R and x ≥ 1