There are four editions of Bartle & Sherbert's Intro to Real Analysis. The posters didn't clarify which.
Keen-ameteur and José Carlos Santos rejected https://math.stackexchange.com/review/suggested-edits/1462452.
Äres rejected, Leucippus approved, José Carlos Santos rejected https://math.stackexchange.com/review/suggested-edits/1462460. The poster omitted two exercise numbers, and omitted details in the book's question. If you don't believe me, I can screen shot.
https://math.stackexchange.com/review/suggested-edits/1462323 and https://math.stackexchange.com/review/suggested-edits/1462321 have no edition or page number. https://math.stackexchange.com/review/suggested-edits/1462321 also didn't use blockquotes to distinguish the book's question from the poster's writing.
Isn't it obvious and common courtesy that posters are supposed to cite books fully, like edition, exercise and page numbers? I'm always nagged when posters don't do this.