How do you solve using gaussian elimination or gauss-jordan elimination, 2x - y + 5z - t = 72xy+5zt=7, x + 2y - 3t = 6x+2y3t=6, 3x - 4y + 10z + t = 83x4y+10z+t=8?

1 Answer
Aug 12, 2017

The solutions are ((x),(y),(z),(t))=((4-2z+t),(1+z+t),(z),(t))

Explanation:

We perform the Gauss Jordan elimination with the augmented matrix

((1,2,0,-3,:,6),(2,-1,5,-1,:,7),(3,-4,10,1,:,8))

R3larrR3-3R1, =>, ((1,2,0,-3,:,6),(2,-1,5,-1,:,7),(0,-10,10,10,:,-10))

R2larrR2-2R1, =>, ((1,2,0,-3,:,6),(0,-5,5,5,:,-5),(0,-10,10,10,:,-10))

R3larr(R3)/(-10), =>, ((1,2,0,-3,:,6),(0,-5,5,5,:,-5),(0,1,-1,-1,:,1))

R2larr(R2)/(-5), =>, ((1,2,0,-3,:,6),(0,1,-1,-1,:,1),(0,1,-1,-1,:,1))

R3larrR3-R2, =>, ((1,2,0,-3,:,6),(0,1,-1,-1,:,1),(0,0,0,0,:,0))

R1larrR1-2R2, =>, ((1,0,2,-1,:,4),(0,1,-1,-1,:,1),(0,0,0,0,:,0))

The solutions are

((x),(y),(z),(t))=((4-2z+t),(1+z+t),(z),(t))

z and t are free