Math Is Fun Forum

rune2402

Banned

Registered: 2007-10-23

Posts: 32

True or false : For every number x, x<13 or x>6

I figure it's true since any number 7-12 would make both statements true.

Not sure though.

mathsyperson

Moderator

Registered: 2005-06-22

Posts: 4,900

Re: True or false : For every number x, x<13 or x>6

Yup. A bit more formally, you can split all numbers into 3 groups: x≤6, 6<x<13 and 13≤x.

For the first group, x<13 is true.
For the second group, both are true.
For the third group, x>6 is true.

Therefore, at least one of them is always true.
Edit: If I'm being really picky, I suppose I should say that at least one of them is true, always.
You know what I mean though.

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Why did the vector cross the road?
It wanted to be normal.

rune2402

Banned

Registered: 2007-10-23

Posts: 32

Re: True or false : For every number x, x<13 or x>6

Thanks buddy.