I want to know about that what is the reason behind of -*- = +
2007-12-23 20:49:04 · 6 answers · asked by tahseen508 1 in Science & Mathematics ➔ Mathematics
This is proved using the real number axioms
http://math.asu.edu/~kawski/classes/mat371/handouts/realaxioms.pdf
The ones beginning with F in particular
These are the basic assumptions used in math to prove all of the rules of numbers
As you are probably not familiar with them I won't give the proof, which actually requires you to prove two lemma's first.
The best way to think of it is using a number line
*The number 6 tells you to walk 6 paces to the right
**The number -6 tells you to turn around then walk 6 paces
(ie walk 6 paces to the left)
***The number -(-6) tells you to turn around then turn around again then walk 6 paces
(ie walk 6 paces to the right)
so it is the same as *, since turning around and then turning around again is the same as not turning around at all
so a -sign basically says, 'turn around and go the other way'
,.,.,
2007-12-23 21:24:01 · answer #1 · answered by The Wolf 6 · 2⤊ 0⤋
This is easy look always think of a numberline.
_________________________
-5 -4 -3 -2 -1 0 1 2 3 4 5 6
If you have -5 and you take away -2 you go on the right so that's why minus and minus is plus is like adding. Because if you add a number you increase it let's suppose you add 1 to 1 you get 2 and you go towards east in the number line you go to your right. That's why and if you add 2 to your -5 you get minus seven and you go on the left so that's why minun plus is minus because is like subtracting. Because if you subtract a number let's suppose you subtract 1 from two you go towards west in the number line you go on your left. That's why if you take away 1 from two you get 1 and you go on your left. So that's why minus minus is plus.
2007-12-23 23:31:35 · answer #2 · answered by Genius 1 · 0⤊ 0⤋
Examples
7 - 5 = 2------------ (2 steps from 5 to 7)
4 - (- 2) = 6-------- (6 steps from - 2 to 4)
The answer of 6 may also be obtained from:-
4 - (-2) = 4 + 2 = 6
2007-12-23 23:31:03 · answer #3 · answered by Como 7 · 0⤊ 0⤋
Look
Assume That:-
Like 3x5=15
so
-3x-5=-15
-(3x5)=-15 (minus cancels)
3x5=15
That why -x-=+
2007-12-23 21:02:14 · answer #4 · answered by Murtaza 6 · 1⤊ 2⤋
well its a mathematical law but don't think that it will be true for real life as "two sinics never make an optimist"
2007-12-23 20:57:20 · answer #5 · answered by nilesh_1991 2 · 1⤊ 0⤋
-*-=+
take two nos
-6&-5
multiply them
ans 30
-&- cancel and + remains
2007-12-23 20:55:21 · answer #6 · answered by yash 3 · 1⤊ 0⤋