Why does minus x minus = plus?

Answer 1

In math, anytime when working with negatives and positives, If you add, subtract or multiply a negative with another negative the answer is always a positive. If the negative is subtracted from a positive and the negative is larger than the positive the answer is a negative, if the positive is larger then the anwer is positive. LIkewise if multiplying a positive with another positive the answer is always a positive. This is just the way mathmeticians set it up centuries ago.

Answer 2

First What does a minus sign mean:

A number added to its additive inverse equals zero.

The minus sign is used to indicate that the number is a additive inverse of the given number.

Say the number is: a, then -a is the additive inverse such that
-a + a = 0

now what is -(-a), it is the number which is the additive inverse of -a.

but we see above the the additive inverse of -a is a.

You asked about minusXminus, so here is an answer:

Draw a number line, with the number a being to the right of zero,
therefore a>0, now multiply by negative 1, then
-a<0, that is the direction of the <, or > sign changes when you multiply by a negative number, this implies a change to the oppsite sign whenever a number is multiplied by a negative number. Try other examples yourself, keeping in mind that -a*-b is the same as (-1)a*(-1)b and using the commutative property to get the number to (-1)*(-1)*ab.

Answer 3

The negatives cancel each other. The best way I can explain it is to consider subtracting a negative number from something.

Lets say you have $6 but you owe $4. $6-$4=$2 so you really only have $2.
Now supose this debt is cancelled, so you now have $2-(-$4).
Since you started with $6 & the debt has been cancelled, you have that original $6.
Therefore $2-(-$4)=$6=$2+$4

Answer 4

First of all, multiplication is repeated addition.
Secondly, addition and subtraction are similar operations..

So, try this:

Add these numbers together 2, 5, 6, -4, 7, 2.

Answer is 18.

Then take away the -4 from the list and add them again.

Answer is 22.

This shows that - -4 is the same as adding 4, so if you remember that multiplication is repeated addition, you should now get it.

Answer 5

here's an easy way

let a be a positive real number

(3a-a)=2a

square each side

(3a-a)^2=4a^2

9a^2 -6a^2 +(-a)^2=4a^2

(-a)^2=4a^2-9a^2+6a^2

(-a) x(-a) = a^2

we stated that a was a positive real number at the start

therefore,minus x minus = plus

Answer 6

ok consider this example... u have 3 apples and u want to give ur GF 5 apples... so u have a minus 2 apples...it means u want 2 apples more....

similarly ur GF's friend also wants to give her 5 apples but she too have 3 apples so even she also wants 2 more apples.... in mathematics she also has -2 apples..

now u and ur GF's friends make an aggrement and say that you both are going to give the apples together... so u have 3 and ur GF's friends has 3 so tottaly u have 6 apples... wait a minute.. u wanted to give 5 to ur GF... so u have one surplus... we are mathematicians .... wow you have one + apple...

thats the reaon why minus*minus is plus

Answer 7

I will prove to you that a negative times a negative equals a positive. I will talk about a number x, that is a product of numbers a and b:

x = ab + (-a)(b) + (-a)(-b)
x = ab + -a(b + (-b))
x = ab + -a*0
x = ab

Also,

x = b(a + (-a)) + (-a)(-b)
x = b*0 + (-a)(-b)
x = (-a)(-b)

Now, combine the two results that you got:

x = (-a)(-b) and x = ab

so,

(-a)(-b) = ab

This shows that when you multiply two negative numbers, you get a positive number.

Answer 8

Think of a - quanity as a debt or something negative. Negating that debt with another - is like cancelling a debt which is a positive result.

Answer 9

minus one nothing multiplied by minus one nothing equals one nothing

Answer 10

It just does, that's math for ya. When will you need all the math B.S. you learn in school? Almost never, but you need it now to pass, lol. That what my Algebra teacher always told us.