Question

please help!!!!!!!!!
2A+3B-4C=7
A-5B+2C=2
-7A-3B+5C=-20
and my prof. answer is (1,-1,-2). I could not get the same answer with him. I tested the answer the first 2 equaltions work out, but the third seems not. Please I really need help!!!!!!!!

Answer 1

I dont know that method. Do you mind helping me step by step:)

Answer 2

I got A=141/57
B=-9/57
the numbers are not pretty so I stop

Answer 3

Oh thank you I will watch it:)

Answer 4

But do you think my Prof. 's answer is not correct???

Answer 5

-7A+3B+5C=-20
that is the 3rd equation

Answer 6

@hartnn yes

Answer 7

u mentioned it incorrectly in question....

Answer 8

maybe u used that incorrect equation to solve...

Answer 9

no the 3rd equation is -7A-3B+5c=-20

Answer 10

how are u so sure ?

Answer 11

2A+3B-4C=7
A-5B+2C=2
-7A+3B+5C=-20
-------------> (1,-1,-2)

Answer 12

3rd: -7A -3B+5C=-20 not -7A+3B+5C=-20

Answer 13

@ktnguyen1 if you have the third equation as you wrote it at first (it's written wrong) then the answer you got for A and B (the ugly numbers) are right. If you use the corrected third equation, as @hartnn said, then the professor's answer is the right one.

Answer 14

2A+3B-4C=7
A-5B+2C=2
-7A-3B+5C=-20
---------->(47/19,-3/19,-12/19)

Answer 15

yes, I think his hand written was wrong!@hartnn, @nincompoop: are correct

Answer 16

Thank so much guys!!!