Optellen geeft \(3x=9\text{,}\) dus \(x=3\text{.}\)

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

De oplossing is \((x, y)=(3, 3)\text{.}\)

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

Aftrekken geeft \(-4y=6\text{,}\) dus \(y=-1\frac{1}{2}\text{.}\)

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

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

\(\begin{cases}3a-4b=5 \\ 5a-6b=2\end{cases}\) \(\begin{vmatrix}3 \\ 2\end{vmatrix}\) geeft \(\begin{cases}9a-12b=15 \\ 10a-12b=4\end{cases}\)

Aftrekken geeft \(-a=11\text{,}\) dus \(a=-11\text{.}\)

\(\begin{rcases}3a-4b=5 \\ a=-11\end{rcases}\begin{matrix}3⋅-11-4b=5 \\ -4b=38 \\ b=-9\frac{1}{2}\end{matrix}\)

De oplossing is \((a, b)=(-11, -9\frac{1}{2})\text{.}\)