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algebra

posted by on .

x+y+z=30
x-y-z=8
x-y+2z=17
x is the same in all equations
y is the same in all equations
z is the same in all equations

  • algebra - ,

    Add the first and the second ---> 2x = 39
    x = 19

    add the first and the third ----> 2x + 3z = 47
    38 + 3z = 47
    z = 3

    now put those values back into the second

    19 - y - 3 = 8
    y = 8

  • algebra - ,

    i am 50 years old, i am sorry but i need this spelled out for me if possible

  • algebra - ,

    Well Steve, I am 68 years old, lol
    I assume you are solving these equations?

    x + y + z = 30 ---- first equation
    x - y - z = 8 -----second equation
    2x + 0 + 0 = 38 ---- I added them
    x = 19 divided by 2, we now know x

    x + y + z = 30 --- first equation again
    x - y + 2z = 17 --third equation
    2x + 0 + 3z = 47 ---- added them

    2x + 3z = 47 , but we know x = 19 so..
    38 + 3z = 47
    3z = 47 - 38
    3z = 9
    z = 3 , so now we have x=19 and z=3

    let's put this back into the first, or any one really

    x + y + z = 30
    19 + y + 3 = 30
    y + 22 = 30
    y = 30-22
    y = 8

    so x=19, y=8, and z=3

    notice those values work in all 3 equations.

  • algebra - ,

    Reiny,thanks so much for your help on this!!!!!!!!!!!

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