Elimination algebra plus#

So the first one, they suggest to subtract Would eliminate a variable in the system of equations? Same question again. Multiple ways to approach solving a system like This is useful to see 'cause you can see there's So actually, all three of these strategies would eliminate a variable

So that actually will eliminate the y's, so I like this choice, as well.

Elimination algebra plus#

Two y plus negative two y, well that's going to be no y's. So two x plus x is going to be three x, so that's not going to eliminate the x's. Four x times 1/2 is going to be two x plus four y times 1/2 is two y is equal to negative two times 1/2 is equal to negative one. All right, let's just multiply times 1/2, so the left hand side times 1/2, we distribute the one half Now what about choice C? Multiply the top equation by 1/2, then add the equations. And then if we subtractĢ0 from negative two, we get to negative 22, but we see that four x minus four x is going to eliminate our x's, so that does definitelyĮliminate a variable, so I like choice B. Subtract negative eight y from four y, well, subtractingĪ negative's the same thing as adding a positive, so that would actually get us to 12 y if we're subtracting That would eliminate the x's, so I'm feeling good about choice B. We multiplied it by four and then subtract the bottomĮquation from the top. What do we get? We're going to get four x minus eight y is equal to 20, yup.

What about choice B? Pause the video, does that work? Multiply the bottom equation by four, then subtract the bottomĮquation from the top equation. I'm gonna delete this so I have space to work Positive four y plus negativeįour y is equal to zero y, so the y's actually do get eliminated when you add four y to negative four y. Four x plus two x is six x, so that doesn't get eliminated. And then if we were to add the equations. Two x, I'm just multiplyingĮverything by two, minus four y is equal to 10. The bottom equation by two, we are going to get, if we multiply it by two, we're gonna get two x minus Pause this video, does that work? All right, so if we multiply The bottom equation by two, then add the equations. Would eliminate a variable in the system of equations? The first choice says multiply One, they're asking us the same question. That's not going to be eliminated, so we can rule that out, as well.

You then add the equations, 10 x plus five x, you're gonna have 15 x, that's not gonna get eliminated. The top equation by two so it's going to become 10 x minus six y is equal to negative six, and you could already see if Does that eliminate a variable? Well we're gonna multiply Top equation by two, then add the equations. Going to be negative nine and so choice B does Three y minus four y is negative seven y. Good about choice B, but then we can see negative We've eliminated an x so I'm already feeling So I won't even write it down, and we've already seen The bottom from the top, five x minus five x, that's going to be zero x's, Subtract the bottom equation from the top. We haven't eliminated any variables, so choice A, I could rule out. One y or just plus y is equal to negative three plus six, which is just going to beĮqual to positive three. Three y plus four y which is just a positive So if we add these equations, we have, on the left hand side, we have five x plus five x, which is going to be 10 x, and then you have negative Would adding the equationsĮliminate a variable in this system? All right, now let's do it together. So this first one says add the equations. Which of these strategies would eliminate a variable in the system of equations? Choose all answers that apply.