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

\(\begin{rcases}3 x + 5 y = -1 \\ x = \frac{1}{2}\end{rcases} \begin{matrix}3 ⋅ \frac{1}{2} + 5 y = -1 \\ 5 y = -2\frac{1}{2} \\ y = -\frac{1}{2}\end{matrix}\)

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

\(\begin{cases}4 p + 2 q = 4 \\ 5 p + q = -4\end{cases}\) \(\begin{vmatrix}1 \\ 2\end{vmatrix}\) geeft \(\begin{cases}4 p + 2 q = 4 \\ 10 p + 2 q = -8\end{cases}\)

Aftrekken geeft \(-6 p = 12 \text{,}\) dus \(p = -2 \text{.}\)

\(\begin{rcases}4 p + 2 q = 4 \\ p = -2\end{rcases} \begin{matrix}4 ⋅ -2 + 2 q = 4 \\ 2 q = 12 \\ q = 6\end{matrix}\)

De oplossing is \((p , q) = (-2 , 6) \text{.}\)

\(\begin{cases}4 a - 6 b = -3 \\ 3 a - 5 b = 4\end{cases}\) \(\begin{vmatrix}5 \\ 6\end{vmatrix}\) geeft \(\begin{cases}20 a - 30 b = -15 \\ 18 a - 30 b = 24\end{cases}\)

Aftrekken geeft \(2 a = -39 \text{,}\) dus \(a = -19\frac{1}{2} \text{.}\)

\(\begin{rcases}4 a - 6 b = -3 \\ a = -19\frac{1}{2}\end{rcases} \begin{matrix}4 ⋅ -19\frac{1}{2} - 6 b = -3 \\ -6 b = 75 \\ b = -12\frac{1}{2}\end{matrix}\)

De oplossing is \((a , b) = (-19\frac{1}{2} , -12\frac{1}{2}) \text{.}\)