Aftrekken geeft \(x = 2 \text{.}\)

\(\begin{rcases}3 x - 4 y = -4 \\ x = 2\end{rcases} \begin{matrix}3 ⋅ 2 - 4 y = -4 \\ -4 y = -10 \\ y = 2\frac{1}{2}\end{matrix}\)

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

\(\begin{cases}2 a + 4 b = -1 \\ 4 a + 5 b = 4\end{cases}\) \(\begin{vmatrix}2 \\ 1\end{vmatrix}\) geeft \(\begin{cases}4 a + 8 b = -2 \\ 4 a + 5 b = 4\end{cases}\)

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

\(\begin{rcases}2 a + 4 b = -1 \\ b = -2\end{rcases} \begin{matrix}2 a + 4 ⋅ -2 = -1 \\ 2 a = 7 \\ a = 3\frac{1}{2}\end{matrix}\)

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

\(\begin{cases}5 p + 3 q = 4 \\ 2 p - 4 q = -1\end{cases}\) \(\begin{vmatrix}4 \\ 3\end{vmatrix}\) geeft \(\begin{cases}20 p + 12 q = 16 \\ 6 p - 12 q = -3\end{cases}\)

Optellen geeft \(26 p = 13 \text{,}\) dus \(p = \frac{1}{2} \text{.}\)

\(\begin{rcases}5 p + 3 q = 4 \\ p = \frac{1}{2}\end{rcases} \begin{matrix}5 ⋅ \frac{1}{2} + 3 q = 4 \\ 3 q = 1\frac{1}{2} \\ q = \frac{1}{2}\end{matrix}\)

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