## zero :(

For students of class 11-12 (age 16+)
leonardo shawon
Posts: 169
Joined: Sat Jan 01, 2011 4:59 pm
Location: Dhaka

### zero :(

im confused.. Amm, whats correct?
real number, R={0,1,2,3,4,5....}
or R={1,2,3,4,5. . . . }
Ibtehaz Shawon
BRAC University.

long way to go .....

tanvirab
Posts: 446
Joined: Tue Dec 07, 2010 2:08 am

### Re: zero :(

I think you mean "Natural numbers".

Different people use different definitions. It does not really matter, as long as your are consistent in what you use.

I personally, use "positive numbers" or "non-negative numbers" to get rid of the ambiguity. This is the most common convention in modern mathematics.

leonardo shawon
Posts: 169
Joined: Sat Jan 01, 2011 4:59 pm
Location: Dhaka

### Re: zero :(

thank u. But actually my question is, is Zero in Positive Real Number Set?
Ibtehaz Shawon
BRAC University.

long way to go .....

leonardo shawon
Posts: 169
Joined: Sat Jan 01, 2011 4:59 pm
Location: Dhaka

### Re: zero :(

thanks 4 Natural Number:) i didnt know that.
Ibtehaz Shawon
BRAC University.

long way to go .....

Moon
Posts: 751
Joined: Tue Nov 02, 2010 7:52 pm
Contact:

### Re: zero :(

Real number is not only integers (পূর্ণ সংখ্যা).They can be fractions, irrational numbers as well. In generals all the numbers on the real line is real numbers.
Zero is not a positive (or negative) real number. You can include zero with positive reals by considering the set of non negative reals. In the same way zero is in the set of non positive reals.
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leonardo shawon
Posts: 169
Joined: Sat Jan 01, 2011 4:59 pm
Location: Dhaka

### Re: zero :(

amm,, then, if f : R - R+
what will i do? Considering Zero as a non negative or Non positive..?
Ibtehaz Shawon
BRAC University.

long way to go .....

tanvirab
Posts: 446
Joined: Tue Dec 07, 2010 2:08 am

### Re: zero :(

As Moon said, zero is not positive, not negative.

leonardo shawon
Posts: 169
Joined: Sat Jan 01, 2011 4:59 pm
Location: Dhaka

### Re: zero :(

so,, where to put it??
First prove for a>0, then a=0 and then a<0 . . . . . . ?
Ibtehaz Shawon
BRAC University.

long way to go .....

tanvirab
Posts: 446
Joined: Tue Dec 07, 2010 2:08 am

### Re: zero :(

Not sure what you mean.

Real numbers \$> 0\$ are positive
Real numbers \$< 0\$ are negative
\$0\$ is neither positive nor negative

leonardo shawon
Posts: 169
Joined: Sat Jan 01, 2011 4:59 pm
Location: Dhaka

### Re: zero :(

okayy., thank uu:-)
Ibtehaz Shawon
BRAC University.

long way to go .....