## alyssababy7 2 years ago Please help! Solve the system of equations using matrices. Use Gaussian elimination with back-substitution. 3x + 5y - 2w = -13 2x + 7z - w = -1 4y + 3z + 3w = 1 -x + 2y + 4z = -5

1. mark_o.

[ 3 5 0 -2 -13 ] [ 2 0 7 -1 -1 ] [ 0 4 3 3 1 ] [ -1 2 4 0 -5 ] can you continue next ?

2. mark_o.

gaussian is to make it like |dw:1354591428681:dw|

3. mark_o.

@alyssababy7 can you follow and do the next steps? .:D let me know.... :D

4. alyssababy7

A. {(-1, -(20/3), 0, 2/5)} B. {(1, -2, 0, 3)} C. {(3/4, -2, 0, 3/4)} D. {(4/3, -(13/20) , 0, 5/2)} My options

5. mark_o.

did you try solving that yet? after back substitution what did you get for x,y,z and w?

6. mark_o.

i did this this way, from [ 3 5 0 -2 -13 ] [ 2 0 7 -1 -1 ] [ 0 4 3 3 1 ] [ -1 2 4 0 -5 ] [ -1 2 4 0 -5 ] mult by -1--> [ 1 -2 -4 0 5 ] [ 0 4 3 3 1 ] [ 0 4 3 3 1 ] [ 2 0 7 -1 -1 ] [ 2 0 7 -1 -1 ] [ 3 5 0 -2 -13 ] [ 3 5 0 -2 -13 ] now its easy to manipulate them to be echelon form

7. alyssababy7

I just don't understand this.

8. mark_o.

[ 1 -2 -4 0 5 ] [ 0 4 3 3 1 ] [ 2 0 7 -1 -1 ] [ 3 5 0 -2 -13 ] try to continue this one tobe gaussian echelon form