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math

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i need help with this problem
2x+2y+3z=-1
3x-5y-2z=21
7x+3y+5z=10

  • math -

    What method have you learned?

  • math -

    EITHER SUBSTITUTION OR ELIMINATION

  • math -

    Ok, elimination then

    work on the z's

    1st times 2 ---> 4x + 4y + 6z = -2
    2nd times 3 ---> 9x - 15y - 6z = 63
    add them
    13x - 11y = 61 (#4)

    2nd times 5 ----> 15x - 25y - 10z = 105
    3rd times 2 ----> 14x + 6y + 10z = 20
    add them
    29x - 19y = 125 (#5)

    going to be messy .....
    #4 times 19 ----> 247x - 209y = 1159
    #5 times 11 ----> 319x - 209y = 1375
    subtract them
    72x = 216
    x = 216/72 = 3 , Yeahhh!
    back in #4

    13(3) - 11y = 61
    -11y = 61-39
    -11y = 22
    y = -2

    back in #1
    2(3)+2(-2) + 3z = -1
    3z = -1 -2
    z = -1

    x=3 , y=-2 , z=-1

  • math -

    CAN ANYONE JUST GET ME HEADED IN THE RIGHT
    DIRECTION ON THIS PROBLEM
    2x+2y+3z=-1
    3x-5y-2z=21
    7x+3y+5z=10

  • math -

    And exactly what did you not like about the solution which is staring at you right above you ?????

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