Review
Recall: Proof methods for a statement
Direct: Assume
is true, prove
is true.
By Contraposition: Assume
is true, prove
that
is true.
By Contradiction: Assume
is true, assume
is true. If a contradiction is found, the proof is
complete.
p
q
p
q
q
p
p
q

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Exercise
Prove by contradiction that
is irrational.
(on board)
2