Optellen geeft \(4a=-8\text{,}\) dus \(a=-2\text{.}\)

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

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

\(\begin{cases}4a-6b=-2 \\ 2a-2b=-6\end{cases}\) \(\begin{vmatrix}1 \\ 3\end{vmatrix}\) geeft \(\begin{cases}4a-6b=-2 \\ 6a-6b=-18\end{cases}\)

Aftrekken geeft \(-2a=16\text{,}\) dus \(a=-8\text{.}\)

\(\begin{rcases}4a-6b=-2 \\ a=-8\end{rcases}\begin{matrix}4⋅-8-6b=-2 \\ -6b=30 \\ b=-5\end{matrix}\)

De oplossing is \((a, b)=(-8, -5)\text{.}\)

\(\begin{cases}5x+4y=1 \\ 3x+3y=-3\end{cases}\) \(\begin{vmatrix}3 \\ 4\end{vmatrix}\) geeft \(\begin{cases}15x+12y=3 \\ 12x+12y=-12\end{cases}\)

Aftrekken geeft \(3x=15\text{,}\) dus \(x=5\text{.}\)

\(\begin{rcases}5x+4y=1 \\ x=5\end{rcases}\begin{matrix}5⋅5+4y=1 \\ 4y=-24 \\ y=-6\end{matrix}\)

De oplossing is \((x, y)=(5, -6)\text{.}\)

Gelijk stellen geeft \(9x+43=2x+8\)

\(7x=-35\) dus \(x=-5\)

\(\begin{rcases}y=9x+43 \\ x=-5\end{rcases}\begin{matrix}y=9⋅-5+43 \\ y=-2\end{matrix}\)

De oplossing is \((x, y)=(-5, -2)\text{.}\)

Substitutie geeft \(3x+4(7x+23)=-32\)

Haakjes wegwerken geeft
\(3x+28x+92=-32\)
\(31x=-124\)
\(x=-4\)

\(\begin{rcases}y=7x+23 \\ x=-4\end{rcases}\begin{matrix}y=7⋅-4+23 \\ y=-5\end{matrix}\)

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

Substitutie geeft \(p=3(5p-25)+19\)

Haakjes wegwerken geeft
\(p=15p-75+19\)
\(-14p=-56\)
\(p=4\)

\(\begin{rcases}q=5p-25 \\ p=4\end{rcases}\begin{matrix}q=5⋅4-25 \\ q=-5\end{matrix}\)

De oplossing is \((p, q)=(4, -5)\text{.}\)