# Math Help - linear system (2)

1. ## linear system (2)

hi
i need little help
$\left\{\begin{matrix}
x+z+t=0\\
ax+y+(a-1)z+t=0\\
x-y+2z+at=0\\
2x+ay+z+2t=0
\end{matrix}\right.$

thanks.

2. Originally Posted by Raoh
hi
i need little help
$\left\{\begin{matrix}
x+z+t=0\\
ax+y+(a-1)z+t=0\\
x-y+2z+at=0\\
2x+ay+z+2t=0
\end{matrix}\right.$

thanks.
To do what? Solve the system of equations? Find the value of a such that these equations have a non-trival solution? That will happen if and only if the determinant is 0.

3. I arrived here,what should i do next ?
$\left\{\begin{matrix}
x+z+t=0\\
y-z+t(1-a)=0\\
-t(1-a)=0
\end{matrix}\right.$

thanks.

4. Originally Posted by Raoh
I arrived here,what should i do next ?
$\left\{\begin{matrix}
x+z+t=0\\
y-z+t(1-a)=0\\
-t(1-a)=0
\end{matrix}\right.$

thanks.
What? What's a variable and what's a constant?

5. $t$ and $a$ are parameters.