Aftrekken geeft \(-3 p = -9 \text{,}\) dus \(p = 3 \text{.}\)

\(\begin{rcases}2 p - 2 q = -3 \\ p = 3\end{rcases} \begin{matrix}2 ⋅ 3 - 2 q = -3 \\ -2 q = -9 \\ q = 4\frac{1}{2}\end{matrix}\)

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

\(\begin{cases}2 x + 2 y = 3 \\ 5 x + 6 y = 6\end{cases}\) \(\begin{vmatrix}3 \\ 1\end{vmatrix}\) geeft \(\begin{cases}6 x + 6 y = 9 \\ 5 x + 6 y = 6\end{cases}\)

Aftrekken geeft \(x = 3 \text{.}\)

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

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

\(\begin{cases}2 x + 2 y = 2 \\ 5 x - 3 y = 1\end{cases}\) \(\begin{vmatrix}3 \\ 2\end{vmatrix}\) geeft \(\begin{cases}6 x + 6 y = 6 \\ 10 x - 6 y = 2\end{cases}\)

Optellen geeft \(16 x = 8 \text{,}\) dus \(x = \frac{1}{2} \text{.}\)

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

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