Mth 163
I have been working on the first problem from the major quiz, and I have run into trouble. I did get the right answer after my second attempt, but the first attempt came out completely wrong. When someone is adding two equations to cancel out a, b, or c, does it matter which equation you add to which or which equation that you multiply by -1 to remove c to make the problem work out correctly? I have checked over my figures several times and see no error in the computations. I have run into this problem before in the homework, and I am very perplexed by the hit or miss outcome that I have been receiving.
The mathematics of the situation is the procedure. The other part is the 'bookkeeping', making sure you don't make any little errors. You can be good with the mathematics while being careless with the bookkeeping. The mathematics is the more important part, but bookkeeping also part of it.
If you're 'hitting' sometimes then you're probably following the correct procedure. There are so many little additions to do that you have to be very careful with your bookkeeping.
Common errors made by people who understand the process include:
adding where you should subtract
multiplying one side of an equation by -1 and neglecting to do so on the other side
incorrect multiplication, addition or subtraction
Even when you're careful it's possible to slip up. I do it all the time. Which is why checking your work is a necessary part of the process.
On a test the main thing I grade is procedure. If your procedure is right and you check correctly, only to find out that something went wrong, you won't be penalized much (1 or 2 points on a 10-point problem).
It makes no difference which equation you multiply by -1 then add to which, as long as the two equations are different, and as long as you use two different pairs to get your two equations in a and b.