How do i write all real numbers in an inequality?

You cannot list them: unless the inequality is trivial, since there are infinitely many real numbers in any range. You need to

• identify the lower bound;
• determine whether or not the lower bound is included (<=) or excluded (<);
• identify the upper bound;
• determine whether or not the lower bound is included (>=) or excluded (<);

And then write the answer as lower bound [< or <=] x [> or >=] upper bound, where x represents you variable.