Aftrekken geeft \(-4 x = 2 \text{,}\) dus \(x = -\frac{1}{2} \text{.}\)

\(\begin{rcases}x - y = 4 \\ x = -\frac{1}{2}\end{rcases} \begin{matrix}-\frac{1}{2} - y = 4 \\ -y = 4\frac{1}{2} \\ y = -4\frac{1}{2}\end{matrix}\)

De oplossing is \((x , y) = (-\frac{1}{2} , -4\frac{1}{2}) \text{.}\)

\(\begin{cases}4 p + 4 q = 4 \\ p - q = -2\end{cases}\) \(\begin{vmatrix}1 \\ 4\end{vmatrix}\) geeft \(\begin{cases}4 p + 4 q = 4 \\ 4 p - 4 q = -8\end{cases}\)

Optellen geeft \(8 p = -4 \text{,}\) dus \(p = -\frac{1}{2} \text{.}\)

\(\begin{rcases}4 p + 4 q = 4 \\ p = -\frac{1}{2}\end{rcases} \begin{matrix}4 ⋅ -\frac{1}{2} + 4 q = 4 \\ 4 q = 6 \\ q = 1\frac{1}{2}\end{matrix}\)

De oplossing is \((p , q) = (-\frac{1}{2} , 1\frac{1}{2}) \text{.}\)

\(\begin{cases}3 a + 4 b = -3 \\ 5 a + 6 b = -1\end{cases}\) \(\begin{vmatrix}3 \\ 2\end{vmatrix}\) geeft \(\begin{cases}9 a + 12 b = -9 \\ 10 a + 12 b = -2\end{cases}\)

Aftrekken geeft \(-a = -7 \text{,}\) dus \(a = 7 \text{.}\)

\(\begin{rcases}3 a + 4 b = -3 \\ a = 7\end{rcases} \begin{matrix}3 ⋅ 7 + 4 b = -3 \\ 4 b = -24 \\ b = -6\end{matrix}\)

De oplossing is \((a , b) = (7 , -6) \text{.}\)