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

\(\begin{rcases}3 x - y = -3 \\ x = -\frac{1}{2}\end{rcases} \begin{matrix}3 ⋅ -\frac{1}{2} - y = -3 \\ -y = -1\frac{1}{2} \\ y = 1\frac{1}{2}\end{matrix}\)

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

\(\begin{cases}2 a - 4 b = -5 \\ a + b = -4\end{cases}\) \(\begin{vmatrix}1 \\ 4\end{vmatrix}\) geeft \(\begin{cases}2 a - 4 b = -5 \\ 4 a + 4 b = -16\end{cases}\)

Optellen geeft \(6 a = -21 \text{,}\) dus \(a = -3\frac{1}{2} \text{.}\)

\(\begin{rcases}2 a - 4 b = -5 \\ a = -3\frac{1}{2}\end{rcases} \begin{matrix}2 ⋅ -3\frac{1}{2} - 4 b = -5 \\ -4 b = 2 \\ b = -\frac{1}{2}\end{matrix}\)

De oplossing is \((a , b) = (-3\frac{1}{2} , -\frac{1}{2}) \text{.}\)

\(\begin{cases}3 p + 4 q = -6 \\ 5 p + 6 q = -6\end{cases}\) \(\begin{vmatrix}3 \\ 2\end{vmatrix}\) geeft \(\begin{cases}9 p + 12 q = -18 \\ 10 p + 12 q = -12\end{cases}\)

Aftrekken geeft \(-p = -6 \text{,}\) dus \(p = 6 \text{.}\)

\(\begin{rcases}3 p + 4 q = -6 \\ p = 6\end{rcases} \begin{matrix}3 ⋅ 6 + 4 q = -6 \\ 4 q = -24 \\ q = -6\end{matrix}\)

De oplossing is \((p , q) = (6 , -6) \text{.}\)