Gaussian elimination assistance

[TonyC]

2 1 1 | 4
-1 2 1 | 3
7 6 5 | 19

Need a little help please

R3+7R2, will get rid of the -7. And will make the bottom row:
0 20 12 | 40

then divide by 2?

 

[stapel]

Sure, that'll work. And then maybe 2R₂ + R₁.

Eliz.

 

[wjm11]

2 1 1 | 4
-1 2 1 | 3
7 6 5 | 19

Need a little help please

R3+7R2, will get rid of the -7. And will make the bottom row:
0 20 12 | 40

then divide by 2?

This all looks fine as a first step, except why divide by just 2? You could divide by 4 to get smaller numbers to work with, or you could even divide by 20 to end up with

0 1 (3/5) | 2

if you don’t mind having the fraction. That gets you a 1 in the second position.

 

[tkhunny]

R2 + 4R1 looks very suspicious.

Do you know what that result means?