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

\(\begin{rcases}a + b = -5 \\ b = 2\frac{1}{2}\end{rcases} \begin{matrix}a + 2\frac{1}{2} = -5 \\ a = -7\frac{1}{2}\end{matrix}\)

De oplossing is \((a , b) = (-7\frac{1}{2} , 2\frac{1}{2}) \text{.}\)

\(\begin{cases}3 p - 2 q = 1 \\ 5 p - 4 q = 4\end{cases}\) \(\begin{vmatrix}2 \\ 1\end{vmatrix}\) geeft \(\begin{cases}6 p - 4 q = 2 \\ 5 p - 4 q = 4\end{cases}\)

Aftrekken geeft \(p = -2 \text{.}\)

\(\begin{rcases}3 p - 2 q = 1 \\ p = -2\end{rcases} \begin{matrix}3 ⋅ -2 - 2 q = 1 \\ -2 q = 7 \\ q = -3\frac{1}{2}\end{matrix}\)

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

\(\begin{cases}2 x - 2 y = -4 \\ 3 x + 3 y = 3\end{cases}\) \(\begin{vmatrix}3 \\ 2\end{vmatrix}\) geeft \(\begin{cases}6 x - 6 y = -12 \\ 6 x + 6 y = 6\end{cases}\)

Optellen geeft \(12 x = -6 \text{,}\) dus \(x = -\frac{1}{2} \text{.}\)

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

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