Question

Help with matrice equations

Answer 1

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