1 . For each 1 in the nonempty index set A let X , be a nonempty subset of R and assume that the union UX , : 1 Ed , is bounded above . Is sup sup X

Please help me answer the following question concerning the supremum of the union of a collection of sets.

1 . For each 1 in the nonempty index set A let X , be a nonempty subset ofR and assume that the unionUX , : 1 Ed , is bounded above . Issup sup X : 1 6 1 3 defined ? Does it equal sup X ? Prove