Reading
Proof by Contradiction can be confusing but the method given at the bottom of page 218 in the Epp textbook is the method we shall use on this course.
1) Suppose the statement to be proved is false (suppose the negative of the statement is true)
2) Show that this supposition leads logically to a contradiction.
3) Conclude that the statement to be proved is therefore true.
Epp Section 4.7 pages 218–221
Video
Now also read Section 4.7 pages 223–225 to be certain you understand the difference between proof by contraposition and proof by contradiction.
Exercises
- Exercise Set 4.7 Questions 12, 16, and 23