jakep069

07-26-2009, 07:50 AM

I have a good grasp of operations on negatice and positive numbers when: +, -, /, *

- * - = +

+ * - = -

- / - = +

- / + = -

a + (-b) = a - b

a - (-b) = a + b

However, if I just stick to the above laws I think I should be alright. Would that be a good solution. My text book has an example trying to use absolute values

eg 2 + (-6) = -(6-2) = -4 - Yes I understand this OK, but they are trying to add it as a step. WHAT FOR ? Is there an actual legitemate reason, or are they just trying to explain a process? I can get from step 1 to the answer without the second step. Is that OK?

Also, in this part of the text there are other examples where eg 12 / 3 = 4, -12 / - 3 = 4, -12 / 3 = -4, -(12 / 3) = -4, and 12 / -3 = -4 - I understand all that NO PROBLEMS, but when doing algebraic math problems with neg operations and in calculus you can be half way through a problem and the lecturer, instructor, or a 'you tube dude' aparently, indescrimenantly just changes an entire math statement from + to -, or does this to an algebraic term, or some sort of expression and I don't know why.

For the above example where there is a - sign in the -12/3, -(12/3) is it for example that it just doesn't matter as the answer is going to be neg anyway. If it is then I just don't know why the signs are being moved. I was watching a hard, algebraic, worked example on you tube and the instructor said 'well I don't want a - numerator, so I will just move it... Who is he? The math god? Why would he have moved it?

Please help.

Jason

- * - = +

+ * - = -

- / - = +

- / + = -

a + (-b) = a - b

a - (-b) = a + b

However, if I just stick to the above laws I think I should be alright. Would that be a good solution. My text book has an example trying to use absolute values

eg 2 + (-6) = -(6-2) = -4 - Yes I understand this OK, but they are trying to add it as a step. WHAT FOR ? Is there an actual legitemate reason, or are they just trying to explain a process? I can get from step 1 to the answer without the second step. Is that OK?

Also, in this part of the text there are other examples where eg 12 / 3 = 4, -12 / - 3 = 4, -12 / 3 = -4, -(12 / 3) = -4, and 12 / -3 = -4 - I understand all that NO PROBLEMS, but when doing algebraic math problems with neg operations and in calculus you can be half way through a problem and the lecturer, instructor, or a 'you tube dude' aparently, indescrimenantly just changes an entire math statement from + to -, or does this to an algebraic term, or some sort of expression and I don't know why.

For the above example where there is a - sign in the -12/3, -(12/3) is it for example that it just doesn't matter as the answer is going to be neg anyway. If it is then I just don't know why the signs are being moved. I was watching a hard, algebraic, worked example on you tube and the instructor said 'well I don't want a - numerator, so I will just move it... Who is he? The math god? Why would he have moved it?

Please help.

Jason