Ask Question
29 February, 04:57

Solve by elimination

-4x-5y-z=18

-2x-5y-2z=12

-2x+5y+2z=4

+3
Answers (2)
  1. 29 February, 06:00
    0
    So

    -4x-5y-z=18

    -2x-5y-2z=12

    -2x+5y+2z=4

    the 2 last equations look perfect for canceling each other so add them together

    -2x-5y-2z=12

    -2x+5y+2z=4 +

    -4x+0y+0z=16

    -4x=16

    divide both sides by 4

    -x=4

    multiply - 1

    x=-4

    now we have

    -4x-5y-z=18

    -2x+5y+2z=4

    add them together

    -6x+0y+z=22

    but x=-4 so

    -6 (-4) + z=22

    24+z=22

    subtract 24 from both sides

    z = - 2

    subsitute into any equation

    -2x-5y-2z=12

    x=-4

    z=-2

    -2 (-4) - 5y-2 (-2) = 12

    8-5y+4=12

    12-5y=12

    subtract 12 from both sides

    -5y=0

    y=0

    x=-4

    y=0

    z=-2
  2. 29 February, 06:35
    0
    -4x - 5y - 1z = 18 ⇒ - 4x - 5y - 1z = 18

    -2x - 5y - 2z = 12 ⇒ - 2x - 5y - 2z = 12

    -2x + 5y + 2z = 4 - 6x - 10y - 3z = 30

    -6 (-4) - 10y - 3z = 30

    -4x - 5y - 1z = 18 24 - 10y - 3z = 30

    -2x - 5y - 2z = 12 ⇒ - 2x - 5y - 2z = 12 - 24 - 24

    -2x + 5y + 2z = 4 ⇒ - 2x + 5y + 2z = 4 - 10y - 3z = 6

    -4x = 16 - 10y + 10y - 3z = 6 + 10y

    -4 - 4 - 3z = 6 + 10y

    x = - 4 - 3 - 3

    z = - 2 - 3¹/₃y

    -10y - 3 (-2 - 3¹/₃y) = 6

    -10y + 6 + 10y = 6

    -10y + 10y + 6 = 6

    0y + 6 = 6

    - 6 - 6

    0y = 0

    0 0

    y = 0

    -10 (0) - 3z = 6

    -0 - 3z = 6

    0 - 3z = 6

    - 0 - 0

    -3z = 6

    -3 - 3

    z = - 2

    (x, y, z) = (-4, 0, - 2)
Know the Answer?
Not Sure About the Answer?
Find an answer to your question ✅ “Solve by elimination -4x-5y-z=18 -2x-5y-2z=12 -2x+5y+2z=4 ...” in 📘 Mathematics if you're in doubt about the correctness of the answers or there's no answer, then try to use the smart search and find answers to the similar questions.
Search for Other Answers