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

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

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

\(\begin{cases}4 x - 2 y = -2 \\ x - y = 4\end{cases}\) \(\begin{vmatrix}1 \\ 2\end{vmatrix}\) geeft \(\begin{cases}4 x - 2 y = -2 \\ 2 x - 2 y = 8\end{cases}\)

Aftrekken geeft \(2 x = -10 \text{,}\) dus \(x = -5 \text{.}\)

\(\begin{rcases}4 x - 2 y = -2 \\ x = -5\end{rcases} \begin{matrix}4 ⋅ -5 - 2 y = -2 \\ -2 y = 18 \\ y = -9\end{matrix}\)

De oplossing is \((x , y) = (-5 , -9) \text{.}\)

\(\begin{cases}6 x + 5 y = -1 \\ 4 x + 2 y = 6\end{cases}\) \(\begin{vmatrix}2 \\ 5\end{vmatrix}\) geeft \(\begin{cases}12 x + 10 y = -2 \\ 20 x + 10 y = 30\end{cases}\)

Aftrekken geeft \(-8 x = -32 \text{,}\) dus \(x = 4 \text{.}\)

\(\begin{rcases}6 x + 5 y = -1 \\ x = 4\end{rcases} \begin{matrix}6 ⋅ 4 + 5 y = -1 \\ 5 y = -25 \\ y = -5\end{matrix}\)

De oplossing is \((x , y) = (4 , -5) \text{.}\)