Answer:
21) x=1, y=-1, z=2 and 23) x=3, y=-1, z=-1
Step-by-step explanation:
there are 3 equations in 21)
1) x+y-z=-2
2)2x-y+z=5
3)-x+2y+2z=1
solve for x by adding equation 2) and 1)
2)2x-y+z=5 + 1) x+y-z=-2 = 3x=3, then divide by 3 and x=1
solve for z by adding equation 1) and 3)
1) x+y-z=-2 + 3)-x+2y+2z=1
we then get a new equation, 4), by isolating z
3y+z=-1 which is 4) z=-1-3y
substitute our new equation, 4) z=-1-3y, and x=1 into equation 1) to get y
(1)+y- (-1-3y)=-2
isolate y to get y=-1
then substitute y=-1 into equation 4) to get z=2
check by substituting x=1, y=-1, and z=2 into all 3 equations
there are 3 equations
1)x+3y=0
2)x+y+z=1
3)3x-y-z=11
add equation 3) and 2) together to get x
3)3x-y-z=11 + 2)x+y+z=1
4x=12, x=3
substitute x=3 into equation 1) (3)+ 3y=0 to get y
3y=-3, y=-1
substitute x=3 and y=-1 into equation 2) to get z
(3)+(-1)+z=1, z=-1
