Thread: A Quick Question on Valid Set Builder Notation

Hello; today my Precalculus teacher gave this definition for the set of rational numbers:

Couldn't this be interpreted to mean that r equals both a/b and a, that b belongs to Z (the set of integers), and that b is not equal to zero?
Shouldn't it be:

or
?
Thanks,
yottaflop

Originally Posted by yottaflop

Hello; today my Precalculus teacher gave this definition for the set of real numbers:

Couldn't this be interpreted to mean that r equals both a/b and a, that b belongs to Z (the set of integers), and that b is not equal to zero?
Shouldn't it be:

or
?
Thanks,
yottaflop

Your Precalculus teacher is wrong!

is set of all rational numbers.

Here you can find some information:

Real number - Wikipedia, the free encyclopedia


Rational number - Wikipedia, the free encyclopedia

Hello, yottaflop!

A few spaces will provode clarity.

. .


I seriously doubt that a textbook would write it like this:

. .


If it does, it may bring back public flogging.

Thank you both; Also sprach: that was a typo on my part, sorry for the confusion. I've edited my original post to fix it.

Originally Posted by Soroban

Hello, yottaflop!

A few spaces will provode clarity.

. .


I seriously doubt that a textbook would write it like this:

. .


If it does, it may bring back public flogging.

I will direct you to this scrappy pack of textbook editors that have decided monkeys para-shooting out of planes and tightrope walking clowns will 'help' explain the math...

Originally Posted by yottaflop

Hello; today my Precalculus teacher gave this definition for the set of rational numbers:

=Couldn't this be interpreted to mean that r equals both a/b and a, that b belongs to Z (the set of integers), and that b is not equal to zero?
Shouldn't it be:

or
?
Thanks,
yottaflop

The second is better than what you initially give. The first of your suggestions is definitely wrong since it is requiring that the set, {a, b}, be an integer!