Register to reply

Disprove the nested quantifier

by albert1992
Tags: disprove, nested, quantifier
Share this thread:
albert1992
#1
Feb20-13, 10:03 PM
P: 11
I have trouble disproving the following expression

Click image for larger version

Name:	Screen Shot 2013-02-20 at 9.01.37 PM.png
Views:	32
Size:	41.5 KB
ID:	55941

I worded it as follows:

The product of certain number and every other nonzero number is 1
Phys.Org News Partner Science news on Phys.org
Security CTO to detail Android Fake ID flaw at Black Hat
Huge waves measured for first time in Arctic Ocean
Mysterious molecules in space
Bashyboy
#2
Feb21-13, 10:49 AM
P: 937
First of all, does the problem specify what the domain is for x and y?

To start, lets back things up a bit. In mathematical terms, the statement is as follows: There exists an x for every possible y value, such that if y isn't zero, when you choose an x-value, you can multiply it by every y-value in the domain, and the result is 1. So, assuming the domain is real numbers, for both x and y, lets try choosing a value for x:

Let x = 5. What value of y would make the statement true? y = 1/5. So, we've tested JUST ONE y-value. x = 5 has to work for EVERY single y. Can you think of a y-value that would make the statement false?


EDIT: If anyone thinks my reply contains fallacious ideas, please inform me.
Bashyboy
#3
Feb22-13, 08:56 AM
P: 937
@Albert, has my reply stirred any thoughts in your mind?


Register to reply

Related Discussions
Disprove the nested quantifier Calculus & Beyond Homework 6
Quantifier help? Set Theory, Logic, Probability, Statistics 1
Universal quantifier Calculus & Beyond Homework 0
Quantifier equivalences Set Theory, Logic, Probability, Statistics 0
Nested Quantifier Calculus & Beyond Homework 10