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yrivers36

  • 2 years ago

Please help me with this system. I'm not getting the y or z. -x+2y+z=2 3x+y+z=12 x-y-2z=-1

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  1. satellite73
    • 2 years ago
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    (3,2,1)

  2. yrivers36
    • 2 years ago
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    Can u explain it to me please?

  3. satellite73
    • 2 years ago
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    are you supposed to use elimation?

  4. yrivers36
    • 2 years ago
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    Either elimination or substitution

  5. satellite73
    • 2 years ago
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    ok we can eleminate z first

  6. selenamalter
    • 2 years ago
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    satellite, i wasnt done, i still needed helpp :/

  7. satellite73
    • 2 years ago
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    \[-x+2y+z=2\] \[ 3x+y+z=12\]

  8. satellite73
    • 2 years ago
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    subtract and get \[-4x+y=-10\] as one equation with no z in it

  9. satellite73
    • 2 years ago
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    now \[3x+y+z=12\] \[ x-y-2z=-1\] multiply first equation by 2 get \[6x+2y+2z=24\] \[x-y-2z=-1\] add and get \[7x+y=23\]

  10. satellite73
    • 2 years ago
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    now we have \[-4x+y=-10\] and \[7x+y=23\] so solve

  11. satellite73
    • 2 years ago
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    subtact second one from first and get \[-11x=-33\] making \[x=3\] now substitute back to find y, and then z

  12. yrivers36
    • 2 years ago
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    Where did the y go in the -4x+y=-10 and 7x+y=23

  13. satellite73
    • 2 years ago
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    i subtracted the second equation from the first

  14. yrivers36
    • 2 years ago
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    oh you multiplied by -1

  15. satellite73
    • 2 years ago
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    or if you prefer, multiply the second by -1 and then add,

  16. satellite73
    • 2 years ago
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    yes exactly it is the same thing

  17. yrivers36
    • 2 years ago
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    ok I got it finally thank you so much for your help

  18. satellite73
    • 2 years ago
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    \[-4x+y=-10\] \[-7x-y=-23\] \[-11x=-33\] etc yw

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