You can
put this solution on YOUR website!multiplication and division are simpler...
-4 x -3 consider the signs then the numbers... - and - is a +, so answer is 12
-4 x +3 ...+ and a - is a -, so answer is -12.
-20/-4 again - and a - is a +, so we get +5 etc
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, as we consider the signs, then the numbers then the letters in turn.
=
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Hopefully, here you can see how regimented the process is - very fixed and structured, never changing. Learn it once, it always applies.
Now for addition and substraction. This is more difficult in that + and - actually stand for 2 things:
+ could mean "ADD" or mean "number is positive" and.
- could mean "SUBTRACT" or mean "number is negative".
eg -3x + -2x means add together the 2 x variables, one having -3 and the other having -2. Now there are tons of explanations on how to treat these things but most just do your head in at some point, so ignore them and just accept that when you have 2 signs TOGETHER that are the SAME... they become a + and
when you have 2 signs TOGETHER that are DIFFERENT.. they become a -.
so in my example above, we have + and -2x --> think of this as a combined -2x, so we get -3x-2x is -5x.
2a+3b-5ab+3a-6a+b-2ab+ac simplifies to (by just looking at the terms and treating all the like terms together) -a+4b-7ab+ac.
How about: Expand and simplify 2x-(2-x)
This actually means 3x - 1(2-x) ie multiply everything in the bracket by -1... so back to multiplication. Doing this first we get 3x - 2 + 2x which then simplifies to 5x - 2
hope this helps?
jon.
