
Help with matrices
HI I'm really close to the answer, but do not know where I went wrong..
Consider the two equations 4x+8y=1 and 2xay=11 ( One is on top of the other) so in matrix form it is
=
For what values of a does the system have a unique solution?
Arranging in augmented matrix and using row operations, I reduced the matrix to
=
I had to invert the matrix premultiplied to the matrix containing x and y, so I had to get the det, I got 8a+32
=
Then I multiplied the determinant into the inversed matrix, simplified, was left with
multiplying them, I get
So my answer is x = .. and y =
but it's wrong.. can someone show me where I went wrong?
Will really appreciate it, thank you so much!

Re: Help with matrices
Hello, Tutu!
First of all, you didn't answer the question.
The system does not have a unique solution if its determinant equals zero.
. .
. . If
. . . .