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Solve the system by addition -2x+5y=-16 and 4x-3y=4?
Not sure where I went wrong or what to do next:
This is what I did..?
2x+2y=-12
2y=-2x-12
y=-x-6
(-2,-4) is the answer
Not sure how to get to that answer though...
Excellent - I see what you mean. Thanks!
Am I solving it by addition when I do it that way?
Taking -x-6 and putting it in for y.
How did you get -4x instead of -2x for the First Equation?
Perfect. Thanks mjj. That explains it perfectly. This is review from over a year ago math class and I was having trouble remembering.
Thanks again.
2 Answers
- YahooLv 61 decade agoFavorite Answer
First equation (multiplied by 2): -4x+10y=-32
Second Equation: 4x-3y=4
Add them get:
7y=-28
y=-4
Choose either equation and replace y:
4x-(-12)=4
4x=-8
x=-2
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The goal is to get one of the variable (either x or y) to be the opposite in the equations. e.g I saw X was already 4 in the second equation and in the first equation I could make -2x.... -4x by multiplying by 2... so thats what I did. That eliminates the X variable allowing you to get Y.
*If you wanted to subtract, you do the same thing except you try to get a variable the same in both equations
- Joshiii AnswersLv 51 decade ago
u get the answer by pluging in in ur answers as y or x the x is -2 and the y is -4 just replace them
