
for every positive integer 1. 6. Give a proof by contradiction that there is no smallest...
give a proof by contradiction. there does not exist any rational number x such that x * sqrt(2) = sqrt(3)
please answer questions #7-13
7. Use a direct proof to show every odd integer is the difference of two squares. [Hint: Find the difference of squares ofk+1 and k where k is a positive integer. Prove or disprove that the products of two irrational numbers is irrational. Use proof by contraposition to show that ifx ty 22 where x and y are real numbers then x 21ory 21 8. 9. 10. Prove that if n is an integer and 3n...
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.
What is wrong with the following proof that every positive integer equals the nex larger positive integer? "Proof," Let P(n) be the proposition that n = n + 1, Assume that P(k) is true, so that k = k + 1 . Add 1 to both sides of this equation to obtain k + 1-k + 2 . Since this is the statement P(k 1), It follows that P(n) is true for all positive integers n.
Q3.a) Show that every planar graph has at least one vertex whose degree is s 5. Use a proof by contradiction b) Using the above fact, give an induction proof that every planar graph can be colored using at most six colors. c) Explain what a tree is. Assuming that every tree is a planar graph, show that in a tree, e v-1. Hint: Use Euler's formula
Q3.a) Show that every planar graph has at least one vertex whose degree...
Proof by contradiction that the product of any nonzero rational number and any irrational number is irrational (Must use the method of contradiction). Which of the following options shows an accurate start of the proof. Proof. Let X+0 and y be two real numbers such that their product xy=- is a rational number where c, d are integers with d 0. Proof. Let x0 and y be two real numbers such that their product xy is an irrational number (that...
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...
1 a). Give a counter example to the proposition: Every positive integer which ends in 31 is a prime. b). Give a proof by cases that min{s, t} + max{s, t} = s + t for any real numbers s and t. Hint: One of the cases you might use is s ≤ t or s < t. Depending on your choice, what would be the other case(s)? c). Give an indirect proof that if 2n 3 + 3n +...
50. What is wrong with this "proof? "Theorem For every positive integer n = (n + /2. Basis Step: The formula is true for n = 1. Inductive Step: Suppose that +Y/2. Then -(+972 +*+- +*+1)/2 + + + /- + 1). By the inductive hypothesis, we have + /2-[(++P/2, completing the + inductive step.
5) [2 marks] Give a proof by contradiction that if n+2 is even then n is even