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Linear equations with two variables

Linear equations with two variables

课程: Test Prep: GRE

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Linear equations with two variables

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- [Voiceover] So sometimes we have linear equations and there are two variables involved. I'll show you what I mean. Let's say I have one equation that's X plus Y equals 10. I can't really solve anything here because if X was two, Y could be eight, or maybe X is five and Y is five, there's actually an infinite number of solutions to that so I can't do much with it but if I did have another equation, let's say X minus Y equals 6, now I can get somewhere, if I have two equations and two variables, generally I will be able to solve. So there's a couple ways to do this. The first way, we're just going to kind of stack the equations, which I kind of already have done and then we want to look for opportunities to add or subtract to make something cancel. This one handily already has that opportunity. If I add these two things, I'll get X plus X is two X, positive Y plus negative Y is zero, and then 10 plus six is 16. And then I can divide both sides by two and I'll find out that X equals…

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