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anonymous

  • 5 years ago

solve using elimination method 5x+5y=-7 7x-2y=13

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  1. anonymous
    • 5 years ago
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    ok, lets eliminate y, and find x first: to eliminate y lets multiply 1st eq by 2 and 2nd eq by -5, to make both Ys cancel each other out once subtracted, so we will have: 10x+10y=-70 -35x+10y=-65 so now we have to subtract coresponding members in both eqs: 45x+0=-5 45x=-5 now divide both sides by a 45 to find x x=-5/45=-0.111

  2. anonymous
    • 5 years ago
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    to find y just substitute it into any of the equations: 5x+5y=-7 5*-0.11111+5y=-7 5y=-7+0.5555 5y=-6.44445 y=-6.44445/5 y = -1.28889 y = -1.289

  3. anonymous
    • 5 years ago
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    now lets see if I was correct, by substituting the values into any eq: 5x+5y=-7 5*-0.1111+5*-1.289= =-7 so I was right and the answers are correct

  4. anonymous
    • 5 years ago
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    got it?

  5. anonymous
    • 5 years ago
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    that doesn't work for the other equation...you messed up somewhere on top

  6. anonymous
    • 5 years ago
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    :/ sorry if I did

  7. anonymous
    • 5 years ago
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    but works for me

  8. anonymous
    • 5 years ago
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    you didn't cancel out y because you had positive 10y on both equations instead of one positive and one negative so that only gave you the right answer for one equation

  9. anonymous
    • 5 years ago
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    ok, so how do I do it?

  10. anonymous
    • 5 years ago
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    do the first equation the same but instead of multiplying second equation by -5 multiply it by 5 so you get 10x + 10y = -14 35x - 10y = 65 this way y really is eliminated then you have 45x = 51 so x = 51/45 which is approximately 1.1333.... plug into either equation and solve 7(1.1333) - 2y = 13 or 7.9331 -2y = 13 after solving for y you get y = -2.53345 now check those two values in both equations

  11. anonymous
    • 5 years ago
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    ok, thanx mate

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