Why do two negatives make a positive?

Answer 1

Think of negative number as meaning the opposite of something. So, if negative is the opposite of positive, then a negative number multiplied or divided by a positive number will give you a negative number. Similarly, multiplying or dividing a negative number by another negative number will give you the opposite of that negative number, which is a positive number.

Answer 2

Two Negatives Make A Positive

Answer 3

If we can agree that a negative number is just a positive number multiplied by -1, then we can always write the product of two negative numbers this way:

(-a)(-b) = (-1)(a)(-1)(b) = (-1)(-1)ab

For example,

-2 * -3 = (-1)(2)(-1)(3)

= (-1)(-1)(2)(3)

= (-1)(-1) * 6

So the real question is,
(-1)(-1) = ?
and the answer is that the following convention has been adopted:

(-1)(-1) = +1

This convention has been adopted for the simple reason that any other convention would cause something to break.

For example, if we adopted the convention that (-1)(-1) = -1, the distributive property of multiplication wouldn't work for negative numbers:

(-1)(1 + -1) = (-1)(1) + (-1)(-1)

(-1)(0) = -1 + -1

0 = -2

Since everything except +1 can be excluded as impossible, it follows that, however improbable it seems, (-1)(-1) = +1.

In other words it is not so much as a rule but rather a convention to make some of the previous assumptions work. It really could mean that the concept of negative numbers introduced conflicts so basic to math itself that this workaround had to be assumed for everything else that follows to work. It could be that negative numbers should fail the distributive property because by their very nature negative numbers would normally do that but mathematicians don't like that.

Answer 4

I know a positive line is a positive - but you really need to speak to the Doctor for a blood test. I've had a fair few faint positives which turned out to be either nothing, a chemical pregnancy, or miscarriage. As you can imagine I was getting very stressed with it all. You are either testing to early - see what MIU the tests are and try and find the lowest (Mine were 10 MIU) A blood test will tell you all. Good luck x P.s Ivan - at 6-8 weeks your HCG levels are in the tens of thousands enough to show on a test) I'm 5 weeks 4 days - at 4 weeks 4 days my HCG were 1145. A test can pick up from 25. Hope this makes sense

Answer 5

(for you physicists out there) you can think of it as an annihilation. If you have a proton (positive one) and an electron (negative one) they collide, and cancel eachother out, leaving you with 0. However, say you were solving
-2- -4.
You start with 2 electrons. However, you cannot subtract 4 electrons when you only have two. since a proton and an electron together sum to 0, you can almost 'import' two pair of protons and electrons, levaing you with 4 electrons and 2 protons. If you take out 4 electrons like stated in the question, you're left with 2 protons, or positive 2. Which is why -2- -4= +2

Answer 6

This Site Might Help You.

RE:
Why do two negatives make a positive?

Answer 7

Two negatives equals a positive?
In a fight, if a fighter loses two (2) points because he was hit two (2) times, he is in NEGATIVE (-) two to his opponent. Take the scales. Start with three (3) ounces of water on each side. Add one more ounce to one (1) side, and it gains weight. Add one more and it gains two, while the other scale has gained nothing. How has the fighter come out as a winner (positive)? Or the scale with no added water a positive? NOT all math is as it may be preached.

Answer 8

- - i - happens? lol

Edit: None these would prove any thing, but if you want to be in fantasy land go ahead make my day?!
A Thumb Down for trying to make your life less complicated?

OK if you insist :

algebraic proof,
consider this. A and B are both positive numbers.
A + (-A) = 0
(A)(B) + (-A)(B) = 0

Since the term on the left is positive, the term on the right must be negative. (I'm assuming here that if two non-zero numbers add up to zero, then one of them is negative and one is positive—I think that is too obvious to require a proof.) This proves that negative times positive is negative. Now:

A + (-A) = 0
(A)(-B) + (-A)(-B) = 0

Since the term on the left is negative (as we just proved!), the term on the right must be positive.

OK?

Answer 9

When dividing any number divided by itself is positive 1(with the exception of 0 since division by 0 is undefined). thus lets look at multiplication -6 X -4. -6/1 *4/-1 = -24/-1 and since we already discussed it for division, then it must be a positive 24

Answer 10

if you make two of them, they make a positive!