Optellen geeft \(6 a = -9 \text{,}\) dus \(a = -1\frac{1}{2} \text{.}\)

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

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

\(\begin{cases}2 x - y = -3 \\ 5 x - 3 y = -4\end{cases}\) \(\begin{vmatrix}3 \\ 1\end{vmatrix}\) geeft \(\begin{cases}6 x - 3 y = -9 \\ 5 x - 3 y = -4\end{cases}\)

Aftrekken geeft \(x = -5 \text{.}\)

\(\begin{rcases}2 x - y = -3 \\ x = -5\end{rcases} \begin{matrix}2 ⋅ -5 - y = -3 \\ -y = 7 \\ y = -7\end{matrix}\)

De oplossing is \((x , y) = (-5 , -7) \text{.}\)

\(\begin{cases}3 p + 2 q = 3 \\ 4 p + 3 q = 1\end{cases}\) \(\begin{vmatrix}3 \\ 2\end{vmatrix}\) geeft \(\begin{cases}9 p + 6 q = 9 \\ 8 p + 6 q = 2\end{cases}\)

Aftrekken geeft \(p = 7 \text{.}\)

\(\begin{rcases}3 p + 2 q = 3 \\ p = 7\end{rcases} \begin{matrix}3 ⋅ 7 + 2 q = 3 \\ 2 q = -18 \\ q = -9\end{matrix}\)

De oplossing is \((p , q) = (7 , -9) \text{.}\)