Question

2x+3y-z=9
x+y+3z=10
2x-8y+10z=-2​

Answer 1

2x+3y-z=9

x+y+3z=10

2x-8y+10z=-2

2x + 3y - z = 9 -> z = 2x + 3y - 9

-> x + y + 3(2x + 3y - 9) = 10 -> 7x + 10y - 27 = 10 -> x = (-10y + 27 + 10)/7 = -10y/7 + 37/7

-> 2(-10y/7 + 37/7) - 8y + 10(2(-10y/7 + 37/7) + 3y - 9) = -2

-> -20y/7 + 74/7 - 8y - 200y/7 + 740/7 + 30y - 90 = -2

-> -220y/7 + 22y + 814/7 - 88 = 0

-> -66y/7 + 198/7 = 0

-> -66y + 198 = 0

-> y = 198/66 = 3

-> x = -10*3/7 + 37/7 = 7/7 = 1

-> z = 2*1 + 3*3 - 9 = 2

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x = 1

y = 3

z = 2