Why Multiplication of Two Negative Numbers Is Positive

I would explain it by number patterns. What does a positive and a negative equal.


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This concept is also explained conceptually by movements on a basic number line.

. A 0 0 and a b c a b a c. So instead of subtracting a negative you are adding a positive. So we can swap that round and use the algebraic properties to prove that it is true.

This in fact is true for any even number of negative numbers multiplied or divided together. 3 2 6 3 1 3 3 0 0. The reason NNP is true is because of the algebraic properties of multiplication.

There is an additive identity 0. The answer to this question is accessible to a 7th grader and should in my opinion be explained as part of every students arithmetic classes. When A decreases from 0 to -1 I tell by students they cant change horses.

Well prove 2 3 6. This video explains why multiplication of two negative integers makes a positive integer. This rule is not obvious and proving it is not straightforward.

Multiplication and Division If two positive numbers are multiplied together or divided the answer is positive. So for consistency the next product in. AA a a0 0a a Addition is commutative.

If a positive and a negative number are multiplied or divided the answer is negative. So your 32 numbers will multipy to a postive. Negative is the opposite of positive.

By Ron Kurtus updated 18 January 2022 When you multiply a negative number by another negative number the result is a positive number. The fact that the product of two negatives is a positive is therefore related to the fact that the inverse of the inverse of a positive number is that positive number back again. First to establish that a positive times a negative is negative.

Negative positive negative -a b - a b or -ab positive negative negative a -b - a b or -ab Then for an expression like 0 0 0 a-a b-b ab - ab - ab -a-b 0 it follows that. Use distributivity of multiplication over addition and other properties of arithmetic to demonstrate. Basically if there is an even number of negatives then it turns to positive but if there is an odd number of negatives then it is a negative.

The first 4 rows of the table follow from the fact that the product of a positive number and a negative number is a negative number which makes perfect sense to most students. To sum up the reason that multiplying two negative numbers makes a positive number is that youre going backwards backwards. This is similar to the way that adding a negative number has the same effect as subtracting a positive number.

Subtracting a negative number from a negative number a minus sign followed by a negative sign turns the two signs into a plus sign. The way I like to explain this is by thinking of real numbers as one-vectors where the magnitude is the distance from the zero and the direction is the sign ie if the number is on the left or right of zero. This is because if you have a negative amount of a negative number it goes positive.

Once we agree that 2 3 6 via repeated addition and 3 2 6 via a belief in commutativity that negative times negative is positive is a forced logical consequence of these next two basic beliefs of arithmetic. Proof that Product of Two Negative Numbers is Positive. Notice in each case as we reduce the second factor by 1 the product is being reduced by 3.

Such that as follows. However here is a clever way to prove the rule by starting with an equation and factoring out terms. So -2 is a one vector.

As the value of numbers in column A decrease by 1 the product of A and B gets bigger by 5. If two negative numbers are multiplied together or divided the answer is positive. You may have heard that two negative numbers multipy to make a positive.

Any product of negative numbers -a -b can have its negatives factored out to -1 -1ab since we know that -x -1x by definition. Multiplying two negative numbers results in a positive number because the product of two negative numbers can be described as the additive inverse of a positive number according to the University of Toronto Mathematics Network. So positive numbers become negative and negative numbers become positive.

That is the meaning of negative multiplication. I dont know if this idea will work for you or if its even mathematically rigorous but it definitely helps me understand multiplying two negative numbers. The negative numbers obey these rules.

Addition and multiplication of integers have various properties known as axioms. So were changing the two negative signs into a positive so the equation now becomes -2 4. AA a b ab ba.

When you multiply any number by a negative number you reverse its sign. I will use the shorthand AA for all EE there exists.


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