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1. Determine whether the following statements are true or false. Prove or dispro

ID: 2987792 • Letter: 1

Question

1. Determine whether the following statements are true or false. Prove or disprove each of the of statements:

(1)  (?a)(?b)(?c)[(a | bc ? a not divide b) =? a | c], in the universe of all integers.

(2)  (?a)(?b)(?c)(?d)[a /b greater than c/d =? ad less than bc], in the universe of all non-zero real numbers.

(3)  (?a)(?b)(?c)(?d)[(a | (b ? 2c) ? a | (c ? d)) =? a | (b ? 2d)], in the universe of all integers.

Hint: Provided a rigorous proof if a statement is true. Give a concrete counterexample if a integers.


2. Claim. For all sets A, B, C and D, if A ? B and C ? D then A ? C ? B ? D.

Explanation / Answer

(1) (?a)(?b)(?c)[(a | bc ? a not divide b) =? a | c], in the universe of all integers. T

(2) (?a)(?b)(?c)(?d)[a /b greater than c/d =? ad less than bc], in the universe of all non-zero real numbers. T

(3) (?a)(?b)(?c)(?d)[(a | (b ? 2c) ? a | (c ? d)) =? a | (b ? 2d)], in the universe of all integers. F