View Full Version : "Opposite Numbers"

John Whitaker

05-09-2006, 10:25 AM

OPPOSITE NUMBERS: My "Complete Idiot's Guide To Algebra" p.9, states: "The opposite of a number is indicated by a lone negative sign out in front of it. For example, the opposite of -3 would be written like this: -(-3). The value of a number's opposite is simply the number multiplied by -1. Therefore, the only difference between a number and it's opposite is its sign."

They offer 2 samples; one of which is a fraction I can not duplicate here. The other is the one that puzzles me: -(4) = -4 I see the signs as the same. Can you explain what I don't see?

Thank you. John :?:

happy

05-09-2006, 10:30 AM

Seems pretty basic to me. Exactly where is your difficulty?

Think of a number line. Then if p is a point on that number line then p is also on the line and is located the same distance from zero as p but on the opposite side of zero.

So what number is the same distance from zero as 3 but opposite zero? Well it is 3! Therefore (3)=-3 and (-4)=4 because 4 is the same distance from zero as 4 but on the other side of zero.

John Whitaker

05-09-2006, 11:55 AM

I get you down to and including: Well it is 3! But -(3)=-3 throws me. What is the difference between (3) and -3 ? Are they both not on the same side of zero?

John Whitaker

happy

05-09-2006, 11:58 AM

What is the difference between (3) and -3 ?

They are exactly the same. It's just another way to represent it. I can represent a number such as "1" by writing "(-1)(-1)", but the result is still "1". Don't overthink it too much.

The reading of (3)=-3 is the negative of 3 is minus 3.

The reading of (-4)=4 is the negative of minus 4 is 4.

It is a matter of words.

John Whitaker

05-09-2006, 12:54 PM

PKA

aHA! I thinkI have it. Thanks. John

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