anonymous one year ago I will fan and medal! 5x+7y=31 2x+4y=16 Which of the following systems could be used to solve the given system of equations by the addition method? 10x + 14y = 31 and -10x - 20y = 16 10x + 14y = 62 and 10x + 20y = 32 -10x - 14y = -62 and 10x + 20y = 80

1. anonymous

im not quite sure what your asking, do you mean which of the bottom system of equations give you the same value as the top system of equations?

2. anonymous

yes i think so @Jdosio

3. anonymous

When you solve a system of equations with the addition method, you want the sign you are getting rid of to be opposite on top and bottom. So for example, 5x and -5x. So we can get rid of one of the choices immediately.

4. anonymous

okay, we can get rid of the 2nd one @LegendarySadist

5. anonymous

Yep. Now look at the other two. See which one of them has a mistake in how it was solved.

6. anonymous

Im not sure how to figure that out @LegendarySadist

7. anonymous

I'm having a hard time trying to figure out how to explain it as well /:

8. anonymous

9. anonymous

Sorry I couldn't be of more help. As a hint, look at the first choice's numbers after the = sign.

A bigger hint: Look closely at the last one.

What do you get when you add them?

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