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1) Voer de vraag zelf uit als leerling
\n2) Randomiseer deze vraag. Vervang de concrete getalletjes door willekeurig getrokken variabelen, maar zorg dat de vraagstelling en modeloplossing nog mooi eruit zien.
\n3) Controleer of de willekeurige getallen altijd even moeilijk zijn, of de randomisatie soms significant moeilijker is. Indien ze moeilijker is, beperk die gevallen bij Variable Testing.
", "licence": "None specified"}, "statement": "The function $f: y=2x^2+2x+c$ has $0$ as an extreme value.
", "advice": "A quadratic function $f:y=ax^2+bx+c$ has a parabolic graph and reaches it extremal value at the vertex.
\nThe $x$-value of the vertex is found as $x=-\\frac{b}{2a}=-\\frac{2}{4}=-\\frac{1}{2}$.
\nThe extremal value itself is given by $f(-\\frac{1}{2})=-\\frac{1}{2}+c$. Since this must be equal to $0$, we find $-\\frac{1}{2}+c=0$, hence $c=\\frac{1}{2}$.
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