5) [2 marks] Give a proof by contradiction that if n+2 is even then n is even
let's assume if n+2 is even, then n is odd taken a value for n+2 which is even. let's take n+2 = 14(an even number) n = 14-2 = 12, which is also an even number. but in the hypothesis, we assumed n to be an odd number. so, by contradiction we proved that if n+2 is even, then n is an even number.
5) [2 marks] Give a proof by contradiction that if n+2 is even then n is...
The sum of two even integers is even (do a proof by contradiction).
Explain the difference between proof by contradiction and proof by contraposition. Give an example of a theorem that would lend itself to proof by contradiction. Explain why that proof technique would be a good choice in this case.
QUESTION 6 1. 2 Give a direct proof that if n' is even, then n is even. [Hint: Consider whether n? +n is odd or even and from that whether n is odd or even.]
Give a proof by contradiction of the following: : If x,y are integers and y is odd, then 2x + y + 1 is even. Given a three element set A: {a1, a2, a3} and a two element set set B: {b1, b2}. Enumerate all the mappings f: A→B.
3) [3 marks] Use a proof by cases that for all real number x, xs]x]. You may need this definition. For any real numbers x, [x]= x, if x2 0, -x, otherwise. 4) [3 marks] Give a direct proof that If x is an odd integer and y is an even integer, then x + y is odd. 5) [3 marks] Give a proof by contradiction for the proposition in Q4, above. That is, give a proof by contraction for...
give a proof by contradiction. there does not exist any rational number x such that x * sqrt(2) = sqrt(3)
for every positive integer 1. 6. Give a proof by contradiction that there is no smallest rational number in the open interval (5,8).
25. (2 points) Below is a proof presented as a proof by contradiction. Restate the proof, using the same ideas, as a proof of the contrapositive of the proposition. Proposition: The sum of a rational number and an irrational number is irrational. Proof: Suppose BWOC that there existr e Q and neR-Q such that run e Q. Sincer is rational, r = for some p, q E Z. Sincer+ne Q, also r+n= for some a, b e Z. Now: r...
Indirect Proofs: Prove Problems 5 - 7 using either proof by contradiction or proof by contraposition. AT LEAST ONE MUST USE PROOF BY CONTRADICTION! 7) For integers c, if c = ab and the ged(a,b) = 1, then a and b are perfect squares. (Hint: If a and b are not perfect squares, what type of number are they?)
7. Give a proof by contradiction that for any subset S of 26 cards from a 52 card deck ( a 52 card deck is composed of 4 suits of 13 cards each), there is a suit such that S has at least 7 cards of that suit. This is an application of the pigeonhole principle.