Aftrekken geeft \(-3 x = -6 \text{,}\) dus \(x = 2 \text{.}\)

\(\begin{rcases}3 x - 4 y = -2 \\ x = 2\end{rcases} \begin{matrix}3 ⋅ 2 - 4 y = -2 \\ -4 y = -8 \\ y = 2\end{matrix}\)

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

\(\begin{cases}5 p - 5 q = 5 \\ p + q = -4\end{cases}\) \(\begin{vmatrix}1 \\ 5\end{vmatrix}\) geeft \(\begin{cases}5 p - 5 q = 5 \\ 5 p + 5 q = -20\end{cases}\)

Optellen geeft \(10 p = -15 \text{,}\) dus \(p = -1\frac{1}{2} \text{.}\)

\(\begin{rcases}5 p - 5 q = 5 \\ p = -1\frac{1}{2}\end{rcases} \begin{matrix}5 ⋅ -1\frac{1}{2} - 5 q = 5 \\ -5 q = 12\frac{1}{2} \\ q = -2\frac{1}{2}\end{matrix}\)

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

\(\begin{cases}3 x + 6 y = 6 \\ 4 x + 5 y = 2\end{cases}\) \(\begin{vmatrix}5 \\ 6\end{vmatrix}\) geeft \(\begin{cases}15 x + 30 y = 30 \\ 24 x + 30 y = 12\end{cases}\)

Aftrekken geeft \(-9 x = 18 \text{,}\) dus \(x = -2 \text{.}\)

\(\begin{rcases}3 x + 6 y = 6 \\ x = -2\end{rcases} \begin{matrix}3 ⋅ -2 + 6 y = 6 \\ 6 y = 12 \\ y = 2\end{matrix}\)

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