Getal & Ruimte (13e editie) - vwo wiskunde B

'Stelsels oplossen'.

vwo wiskunde B 4.1 Stelsels vergelijkingen

Stelsels oplossen (6)

opgave 1

Los exact op.

3p

a

\(\begin{cases}a+6b=-5 \\ 4a-6b=-5\end{cases}\)

Eliminatie (1)
003f - Stelsels oplossen - basis - 361ms - dynamic variables

a

Optellen geeft \(5a=-10\text{,}\) dus \(a=-2\text{.}\)

1p

\(\begin{rcases}a+6b=-5 \\ a=-2\end{rcases}\begin{matrix}-2+6b=-5 \\ 6b=-3 \\ b=-\frac{1}{2}\end{matrix}\)

1p

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

1p

4p

b

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

Eliminatie (2)
003g - Stelsels oplossen - basis - 15ms - dynamic variables

b

\(\begin{cases}4a+2b=-1 \\ 3a+b=-4\end{cases}\) \(\begin{vmatrix}1 \\ 2\end{vmatrix}\) geeft \(\begin{cases}4a+2b=-1 \\ 6a+2b=-8\end{cases}\)

1p

Aftrekken geeft \(-2a=7\text{,}\) dus \(a=-3\frac{1}{2}\text{.}\)

1p

\(\begin{rcases}4a+2b=-1 \\ a=-3\frac{1}{2}\end{rcases}\begin{matrix}4⋅-3\frac{1}{2}+2b=-1 \\ 2b=13 \\ b=6\frac{1}{2}\end{matrix}\)

1p

De oplossing is \((a, b)=(-3\frac{1}{2}, 6\frac{1}{2})\text{.}\)

1p

4p

c

\(\begin{cases}5x-4y=6 \\ 4x-3y=6\end{cases}\)

Eliminatie (3)
003h - Stelsels oplossen - basis - 12ms - dynamic variables

c

\(\begin{cases}5x-4y=6 \\ 4x-3y=6\end{cases}\) \(\begin{vmatrix}3 \\ 4\end{vmatrix}\) geeft \(\begin{cases}15x-12y=18 \\ 16x-12y=24\end{cases}\)

1p

Aftrekken geeft \(-x=-6\text{,}\) dus \(x=6\text{.}\)

1p

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

1p

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

1p

4p

d

\(\begin{cases}y=7x+3 \\ y=4x\end{cases}\)

GelijkStellen
003i - Stelsels oplossen - basis - 2ms

d

Gelijk stellen geeft \(7x+3=4x\)

1p

\(3x=-3\) dus \(x=-1\)

1p

\(\begin{rcases}y=7x+3 \\ x=-1\end{rcases}\begin{matrix}y=7⋅-1+3 \\ y=-4\end{matrix}\)

1p

De oplossing is \((x, y)=(-1, -4)\text{.}\)

1p

opgave 2

Los exact op.

4p

a

\(\begin{cases}3p+2q=-3 \\ q=7p+24\end{cases}\)

Substitutie (1)
003j - Stelsels oplossen - basis - 3ms - dynamic variables

a

Substitutie geeft \(3p+2(7p+24)=-3\)

1p

Haakjes wegwerken geeft
\(3p+14p+48=-3\)
\(17p=-51\)
\(p=-3\)

1p

\(\begin{rcases}q=7p+24 \\ p=-3\end{rcases}\begin{matrix}q=7⋅-3+24 \\ q=3\end{matrix}\)

1p

De oplossing is \((p, q)=(-3, 3)\text{.}\)

1p

4p

b

\(\begin{cases}x=5y+1 \\ y=7x+27\end{cases}\)

Substitutie (2)
003k - Stelsels oplossen - basis - 1ms - dynamic variables

b

Substitutie geeft \(x=5(7x+27)+1\)

1p

Haakjes wegwerken geeft
\(x=35x+135+1\)
\(-34x=136\)
\(x=-4\)

1p

\(\begin{rcases}y=7x+27 \\ x=-4\end{rcases}\begin{matrix}y=7⋅-4+27 \\ y=-1\end{matrix}\)

1p

De oplossing is \((x, y)=(-4, -1)\text{.}\)

1p

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