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

\(\begin{rcases}6 p + q = 2 \\ p = -\frac{1}{2}\end{rcases} \begin{matrix}6 ⋅ -\frac{1}{2} + q = 2 \\ q = 5\end{matrix}\)

De oplossing is \((p , q) = (-\frac{1}{2} , 5) \text{.}\)

\(\begin{cases}a + b = 3 \\ 5 a + 3 b = 3\end{cases}\) \(\begin{vmatrix}3 \\ 1\end{vmatrix}\) geeft \(\begin{cases}3 a + 3 b = 9 \\ 5 a + 3 b = 3\end{cases}\)

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

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

De oplossing is \((a , b) = (-3 , 6) \text{.}\)

\(\begin{cases}5 x - 5 y = 5 \\ 4 x - 6 y = -3\end{cases}\) \(\begin{vmatrix}6 \\ 5\end{vmatrix}\) geeft \(\begin{cases}30 x - 30 y = 30 \\ 20 x - 30 y = -15\end{cases}\)

Aftrekken geeft \(10 x = 45 \text{,}\) dus \(x = 4\frac{1}{2} \text{.}\)

\(\begin{rcases}5 x - 5 y = 5 \\ x = 4\frac{1}{2}\end{rcases} \begin{matrix}5 ⋅ 4\frac{1}{2} - 5 y = 5 \\ -5 y = -17\frac{1}{2} \\ y = 3\frac{1}{2}\end{matrix}\)

De oplossing is \((x , y) = (4\frac{1}{2} , 3\frac{1}{2}) \text{.}\)