[Solution] (5 points each) Short Answer Write the negation of the following in readable form: " ∃ w such that ∀ z, if z 2 > w. Find a counter
Question: (5 points each) Short Answer
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Write the negation of the following in readable form: " \(\exists w\) such that \(\forall \) z, if z
2 > w. - Find a counter example for " \(\forall n\in \mathbb{Z},\exists k\in \mathbb{Z}\) such that \(k\cdot n=12\) "
- What is the range of the function \(f:\mathbb{R}\to \mathbb{R}\) defined by f(x) = 3x 2 + 4.
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What is wrong the following proof by mathematical induction that: \(\forall n\in \mathbb{N}\),
2n +1 <2(n -1) + 1?
Let P(n) be the statement 2n + 1 < 2(n - 1) + 1 and assume that k \(\in \) N and that P(k) is true. (We’ll prove P(k + 1) is true.) P(k) is the statement 2k + 1 < 2(k - 1) + 1. Adding 2 to both sides of this inequality gives 2k + 2 + 1 < 2(k-1) +2+1. The left hand side of this inequality is equal to 2(k + 1) + 1 and the right hand side is 2((k + 1) 1) + 1. Therefore we have 2(k + 1) + 1 < 2((k + 1) 1) + 1 and this is P(k + 1). (You don’t have to tell me that the statement being proved is false. I want to know what’s wrong with the proof.) - Give a formula for a one to one function from (0, 1) onto (3, 7).
- Give an example of an innite set A for which A< R.
- For the relation R = (21)(22)(12)(34)which of the following properties hold: symmetric, transitive, anti-symmetric.
- For the relation R dened on R by x R y if and only if x y2nd an example which shows that R is not transitive.
- Give an example of a transitive, symmetric relation which is not anti-symmetric.
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