Question

Solve the following equations by using
Cramer’s rule:
1. x – y – 2z = 1; 2x + 3y + 4z = 4; 3x – 2y – 6z = 5.

Answer 1

Answer:

D =

[1−1−2 234 3−2−6]

= 1(-18+8)+1(-12-12)-2(-4-9)

=-8

Dx =

[1−1−2 434 5−2−6]

= 1(-18+8) +1(-24-20) -2(-8-15)

= -8

therefore, X=DxD=−8−8=1

Dy =

[11−2 244 35−6]

=1(-24-20) -1(-12-12)-2(10-12)

=-16

therefore, y = DyD=−16−8=2

Dz =

[1−11 234 3−25]

=1(15+8) +1(10-12)+1(-4-9)

= 8

therefore, y = DzD=8−8=−1