[tex]\begin{bmatrix}4x+4y=0\\ -4x-4y=0\end{bmatrix}[/tex]
Subtract 4y from both sides.
[tex]4x+4y-4y=0-4y[/tex]
Simplify
[tex]4x=-4y[/tex]
Divide each side by 4
[tex]\frac{4x}{4}=\frac{-4y}{4}[/tex]
Simplify
[tex]x= -y[/tex]
Substitute x as -y.
[tex]\begin{bmatrix}-4\left(-y\right)-4y=0\end{bmatrix}[/tex]
[tex]0=0[/tex]
The values of x and y are both zero.