Aftrekken geeft \(-2p=-3\text{,}\) dus \(p=1\frac{1}{2}\text{.}\)

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

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

\(\begin{cases}a+b=-3 \\ 4a-2b=-3\end{cases}\) \(\begin{vmatrix}2 \\ 1\end{vmatrix}\) geeft \(\begin{cases}2a+2b=-6 \\ 4a-2b=-3\end{cases}\)

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

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

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

\(\begin{cases}6x-4y=-6 \\ 4x-3y=6\end{cases}\) \(\begin{vmatrix}3 \\ 4\end{vmatrix}\) geeft \(\begin{cases}18x-12y=-18 \\ 16x-12y=24\end{cases}\)

Aftrekken geeft \(2x=-42\text{,}\) dus \(x=-21\text{.}\)

\(\begin{rcases}6x-4y=-6 \\ x=-21\end{rcases}\begin{matrix}6⋅-21-4y=-6 \\ -4y=120 \\ y=-30\end{matrix}\)

De oplossing is \((x, y)=(-21, -30)\text{.}\)