positive and negative numbers...?

Question

what is important to remember when multipling/ dividing positive and negative numbers? and ... what is impotant to remember when adding/ subtracting positive and negative numbers? i really need help with my math lol =]

Answer 1

Here are a whole bunch of rules. I have made them as simple as possible (By the way * means multiply and / means divide. a and b are any numbers):

Addition and subtraction: two minus signs directly in a row means "add".

a+b = a+b
a+(-b) = a-b
a-(-b) = a+b
-a+b = b-a
-a-b = -(a+b)

Multiplication and Division: If there are an EVEN number of minus signs then the answer will be POSITIVE. If there are an ODD number of minus signs the answer will be NEGATIVE.

a*b = a*b
a*(-b) = -(a*b)
(-a)*b = -(a*b)
(-a)*(-b) = a*b

a/b = a/b
a/(-b) = -(a/b)
(-a)/b = -(a/b)
(-a)/(-b) = a/b

Answer 2

Multiplication /division (X)

(+ x +) = +
(+ x - ) = -
(- x + ) = -
(- x -) = +

Addition/Subtraction

Best shown as examples:-

5+ 3 = 8
5 - 3 = 2
-3 + 5 = 2
-5 + 3 = -2
3 - 5 = -2
-3 -5 = -8

NB If no operational sign is indicated, then it is always read as '+'.

Hope this helps!!!!

Answer 3

ok, no big deal here! :)

negative nr * negative nr = positive number

negative nr * positive nr = negative number

examples:

-10 + 5= -5
15 - 7= 8

3 * (-4) = -12
-3 * (-3) = 9

Hope that helps. you'll get it if you practice a little bit!

Answer 4

when you are multiplying
neg x neg = pos
pos x pos = pos
pos x neg = neg
neg x pos = neg

when subtracting
neg/pos - neg =
the sub sign and neg sign turns into a addition and pos sign