The union of s and t is r, and the set of all real numbers is usually referred to as real number set for short, and is recorded as R.

A complex set counts as C.

If the absolute value of S={x│x-2 is greater than 3}, then x >；; 5 or x

t = { x│a & lt； X & ltA+8}, then A.

Because S∪T=R, a+8 >: 5 and a <-1

All in all -3

S and t are United. If there is intersection, a+8 >; 5 or a

Only when a>- 1 and a+8.