What Is -9+4 Equal ?

4

4 Answers

Ellie Hoe Profile
Ellie Hoe answered
Here are some rule : I will take 9 as first number and 4 as second number in the example

If both the number have negative sign (-) then you will add both the number and put "-" sign with the end result e.g -9-4= - 13

If one number has negative sign "-" and other has positive "+" sign then you will subtract the number and put the sign of the biggest number with the end result. E.g

As in question
First number is - 9
Second number is +4
You will subtract 9 from 4 and put the sign of bigger number with the end result. So the answer is
 
-9 + 4 = - 5 >>> answer
thanked the writer.
Richard Enison
Richard Enison commented
Just about everyone got the right answer, but your explanation gave the "cookbook" rules for algebraic addition without motivating them. I think Oddman's explanation makes it more intuitively understandable.
Oddman Profile
Oddman answered
The commutative property of arithmetic allows you to put the numbers in a comfortable order: -9 + 4 is the same as 4 - 9 = -5.

On a horizontal number line with positive to the right, the sum is represented by 9 steps left, then 4 steps right (or 4 steps right and 9 steps left, if you prefer). Either way, you end up 5 steps to the left of where you started, at the point that represents -5.

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