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View Full Version : Find the solution to the system of equations given below using elimination by addit


roanna
Jan 17, 2012, 02:32 PM
5x + 2y = -32
9x + 10y = -16

ebaines
Jan 17, 2012, 03:19 PM
Roanna: please be aware that you can't copy and paste equations from other applications into this web site - they don't come out right. I have taken the liberty of editing your post to what I think you meant. Please let me know if what I did is not correct.

The objective is to eliminate either the x or y variables by combining the two equations. To get started it helps to look for where variables have same or similar coefficients in front of them. For example note that the coefficients for y in the two equatons are 2 and 10 respectively, and so if you multiply the first equation through by a factor of 5 you will end up with the y variable having a coefficient of 10:

5(5x+2y) = 5(-32), or
25x + 10y = -160

Now you can subtract the second equation from this:

25x + 10y - (9x + 10y) = -160 -(-16), or:
16x = -144

Now you can solve for x, and use that value to substiturte back into either one of the first set of equations, and that will let you solve for y. Post back with what you get for a final answer and we'll check it for you.