I can understand the double positive thing okay, but the double negative confuses me: if I say, 'No, No, a thousand times No!' how can that then mean yes? I am using a linguistic example as I find it easier to think in words, but I realise this might be where I am going wrong.
But how can -1 + -1 NOT equal -2?
I really would like an answer to this as it has puzzled me since schooldays.
2007-01-07 01:33:49 · 15 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
Thanks, Marina - that link looks good and I will studiy it! I know that adding two negaitive numbers together always produces a negative but I think what I mean is, why do people say that two negatives make a positive?
2007-01-07 01:44:35 · update #1
Ah, multiplication - that msyterious beast - now it is becoming clear ... (yet I alwasy believed multiplication to be a shorthand way of adding lots of numbers together, so how does it change the direction the numbers are going in?)
2007-01-07 01:47:44 · update #2
Eureka! I see it now - what you are left with after multiplying two negatives is the DIFFERENCE between the two numbers! I just never saw that before - the number line makes it all so simple and I wish we had had that at school! Thanks to all of you - most interesting!
2007-01-07 01:58:48 · update #3
I assume from your example that you are talking about addition and subtraction.
Example 1
(-2) + (-3) =(-5)
This may be read on the number line as 2 steps left and then 3 steps left. This takes you 5 steps left.
Answer is thus (-5)
Example 2
8 - 5 can be read as "How many steps from 5 to 8?"
The answer is 3
Example 3
7 - (-3) can be read "How many steps from (-3) to 7?"
The answer is 10.
This suggests that 7 - (-3) = 7 + 3 =10
i.e. "two minuses have made a positive."
Hope these examples are of use.
2007-01-07 05:35:49 · answer #1 · answered by Como 7 · 1⤊ 0⤋
Linguistically, -1 x -1 is like saying a double negative and having it become a positive. For example, if I say, "I am not going to school," that is a negative. However, if I say, "I am not not going to school," that literally translates into saying that I am going to school, ie. a positive.
Another good example is the common mistake of saying something like, "I don't have no money," which literally translates in the positive statement that you do indeed have some money.
2007-01-07 01:50:09 · answer #2 · answered by mark w 2 · 1⤊ 0⤋
You are in fact correct that the sum, -1 + =1 = -2. But the product, (-1)*(-1) is +1. When you use a negative in language, it becomes similar to a logical statement for which the product is the appropriate operation. For verbal statements (logic), every time you "add" a negative to the sentence, it inverts the meaning, as does multiplying by -1.
2007-01-07 01:43:18 · answer #3 · answered by bmord1 1 · 1⤊ 0⤋
Two negatives only make a positive in multiplication, not addition. When you multiply by a negative, you are switching the direction on the number line that you are going. If you are already going in the negative direction and you multiply by a negative, you are actually switching back to the positive direction.
2007-01-07 01:43:20 · answer #4 · answered by Brian S 2 · 2⤊ 0⤋
-1 + -1 = -2, you are correct!
But when you multiply 2 negative numbers, that's when double negative becomes positive: -1 * -1 = 1
2007-01-07 01:42:29 · answer #5 · answered by Anonymous · 1⤊ 0⤋
-1 + -1 = -2
buuut
1 - (-1) = 2
and
-1 -(-1) = 0
and
-1 x -1 = 1
i have an excellent way to think about it! draw a number line! when you "add" a number, you travel to the right (towards positive direction) on the number line. when you 'subtract' you go the OPPOSITE way! so if you subtract a negative number, you go the opposite of the opposite way ("double negative") which is the positive way! get it?
2007-01-07 04:57:38 · answer #6 · answered by Anonymous · 0⤊ 0⤋
-1+-1 does equal -2.
However -1- -1 = 0
When u minus a minus number it becomes a positive number!
2007-01-07 01:44:42 · answer #7 · answered by Anonymous · 1⤊ 0⤋
i think undesirable fer her scholars. besides and subtraction you in consumer-friendly words do the mathematics contained in the line. till it become (a million+5)-(2+3) you would possibly want to by no ability get a million. no matter if you blend the plus indicators you get a million+5+3=9-2=7. youd could function each of the numbers like this a million+5+(-2)+3=7. you ought to have had alot of failing scholars below you. damn thats smiple math and also you &*^%#$ it up.
2016-12-28 07:29:06 · answer #8 · answered by Anonymous · 0⤊ 0⤋
It's the + - X % sign which tell you the process.
So -1 take away -1 leaves nothing
but -1 add another -1 gives does you -2
It takes a bit of doing but thing you have a -1 in your hand and your going to add or take away from it etc.
2007-01-07 01:47:12 · answer #9 · answered by Anonymous · 0⤊ 0⤋
If you add 2 negative numbers together then the answer will ALWAYS be negative..
2007-01-07 01:40:42 · answer #10 · answered by Anonymous · 0⤊ 0⤋