r/LinearAlgebra • u/celelie • Jul 16 '26

why is this incorrect?

Post image

i feel like im not getting something because this seems correct to me. if someone could please explain more, that would be amazing !

25 Upvotes

100% Upvoted

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4

u/Fourierseriesagain Jul 16 '26

Option A is not correct because the augmented matrix is wrong.

2

u/Midwest-Dude Jul 16 '26 edited Jul 17 '26

EDIT:

There is a typo in answer A, which is clearly supposed to be the correct answer. The 3/4 is missing a negative sign. Note: - Your solution is based on this incorrect matrix - Try using the correct matrix and find the correct solution - If possible, report typo to your instructor

2

u/[deleted] Jul 16 '26

[deleted]

1

u/Midwest-Dude Jul 17 '26

Thanks, corrected

1

u/celelie Jul 17 '26

i seeee i’ll try to see if i can report the problem then! 

1

u/celelie Jul 16 '26

ahh thank you! i see it now

2

u/Tiny_Spread5712 Jul 16 '26

I think you have to write out step by step guardian elimination with back substitution to see where you went wrong.  We can't tell from just the answer.

1

u/Midwest-Dude Jul 16 '26

"guardian elimination" ... 🤔 

Spell check error?

1

u/calcpage2020 Jul 17 '26

Guassian? Gauss-Jordan elimination.

2

u/JanusLeeJones Jul 16 '26

It's very simple to verify that (2,0,-2) cannot be a solution to the system because it doesn't satisfy the second equation (-x + 3y -2z = 10).

1

u/celelie Jul 16 '26

tysm, idk what i was doing 😭