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ray_mezz2002
May 10, 2007, 02:15 PM
:confused: I need help trying to solve linear equations.. I don't even know where to start.. :confused:

colbtech
May 15, 2007, 02:45 AM
I presume you have something like:
2x + 3y = 13
6x + 4y = 24

Solve x and y. You need to cancel one of the unknowns.. first multiply all terms in equation 1 by 3. So...

2x + 3y = 13 becomes 6x +9y = 39

next subtract equation 1 (new) from equation 2. So...

6x + 9y = 39 (equation 1 new)
- 6x + 4y = 24 (equation 2)
_____________
5y = 15

Next divide both sides by 5 to give y...

y = 15/5
y = 3

So now you know y, substitute y into equation 1.

2x + 3y = 13, which gives 2x + 3*3 = 13
2x + 9 = 13 (subtract 9 from both sides)
2x = 13-9
2x = 4 (divide both sides by 2)
x = 2

To check:

Sustitute the values for x & y into equation 2.

6x + 4y = 24

gives (6*2) + (4*3) = 24

12 + 12 = 24

Should be able to work out all sorts now. Remember when multiplying 2 negative values the result is positive!

angelinside94
Jun 22, 2007, 11:13 AM
Im in the 8th grade and I just passed Algebra and what colbtech just said is exactly how I learned it and I got the Top Academic award so that should help.