SOLUTION: Hi, I'm having trouble with this question. I don't know how I'm supposed to work it out, so any help would be great appreciated! Thank you! Determine the values for "a" for which

Algebra.Com
Question 1050415: Hi, I'm having trouble with this question. I don't know how I'm supposed to work it out, so any help would be great appreciated! Thank you!
Determine the values for "a" for which the following system of linear equations has no solutions, a unique solution, or infinitely many solutions. I need to solve using a matrix, and then row reducing.
3X1 + aX2 + 6X3 = 6
-X1 + 3X2 - X3 = 1
2X1 - 2X2 + 6X3 = 11

Answer by stanbon(75887)   (Show Source): You can put this solution on YOUR website!
Determine the values for "a" for which the following system of linear equations has no solutions, a unique solution, or infinitely many solutions. I need to solve using a matrix, and then row reducing.
3X1 + aX2 + 6X3 = 6
-X1 + 3X2 - X3 = 1
2X1 - 2X2 + 6X3 = 11
------------------------
You have to find the determinant of the "coefficient matrix"::
--------
D = (3*3*6 + (-1*2*6) + (2*-1*a) - [(6*3*2)+(-1*-2*3)+(6*-1*a))
----
D = (54 - 12 - 2a - [36 + 6 - 6a])
----
D = (42-2a)-(42-6a)
---
D = 4a
-----
One unique solution if a is not zero
No solution when a = 0
----
I'll leave the row reducing to you.
Cheers,
Stan H.
-------------

RELATED QUESTIONS

Hi, I'm having trouble with this question. I don't know how I'm supposed to work it out,... (answered by robertb)
Hi! I have a question that I'm having trouble with. I started to work on it but I'm not... (answered by stanbon)
I am having a lot of trouble with word problem questions. If someone could help me that... (answered by Edwin McCravy)
Hello! I am having trouble with my homework and I would be very happy if someone could... (answered by Earlsdon)
Hi! So I am having trouble with Subsitiution. With this question is says to either solve... (answered by oscargut,checkley71)
Hi ive been having alot of trouble figuring out the answer to this question i mean i know (answered by stanbon,galactus)
Hello, I am having a problem finding the equation for a hyperbola. I have tried to work... (answered by lwsshak3)
i''m having trouble understanding how these problems work this is the problem.. S = 12.75 (answered by Cromlix,solver91311)
Claim: The proportion of brown M&Ms more than 22%. A simple random sample of 150 M&Ms... (answered by stanbon)