Solve using any method Make sure your steps are clearly stat

Solve using any method. Make sure your steps are clearly stated. {x - 2y - 2z = 11 3x + 4y - z = -2 4x + 5y + 7z = 7

1. three equations are

x-2y-2z=11........... (i)

3x+4y-z=-2..............(ii)

4x+5y+7z=7............. (iii)

3*(i) -(ii) we get

3x-6y-6z-3x-4y+z=33+2 or, -10y-5z=35 or, 2y+z=-7..... (iv)

4*(i)-(iii) we get

4x-8y-8z-4x-5y-7z=44-7 or, -13y-15z=37 or, 13y+15z=-37.....(v)

15*(iv)-(v) we get 30y+15z-13y-15z=-105+37 or, 17y=-68 or y=-4

hence z=-7-2(-4)=1 [from iv]

hence x-2*(-4)-2*(1)=11 or,x=5

hence the solution is x=5, y=-4 and z=1 [answer]