Lettervormen getalwaarde

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Bereken de getalwaarde

1. \(5ab-4b-15\text{ [met a = -2 en b = -1]}\)
2. \(a-6b\text{ [met a = 1 en b = -3]}\)
3. \(a^2+3b\text{ [met a = -5 en b = -2]}\)
4. \(3ab+4b+9\text{ [met a = 2 en b = -4]}\)
5. \(4a^2+6b\text{ [met a = -5 en b = 3]}\)
6. \(3a+5b\text{ [met a = -3 en b = -2]}\)
7. \(3a^2-b\text{ [met a = 6 en b = -2]}\)
8. \(6a+2b\text{ [met a = 1 en b = 5]}\)
9. \(2ab-b-15\text{ [met a = -3 en b = 4]}\)
10. \(4ab+b-6\text{ [met a = 2 en b = 5]}\)
11. \(2ab+5b-8\text{ [met a = 4 en b = 2]}\)
12. \(10a+4b\text{ [met a = 3 en b = 3]}\)

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Bereken de getalwaarde

Verbetersleutel

1. \(\begin{align} 5ab-4b-15&=5.a.b-4.b-15 \text{ [met a = -2 en b = -1]}\\&=5.(-2).(-1)-4.(-1)-15\\&=-1\\ \end{align}\)
2. \(\begin{align} a-6b&=1.a-6.b \text{ [met a = 1 en b = -3]}\\&=1.1-6.(-3)\\&=19\\ \end{align}\)
3. \(\begin{align} a^2+3b&=1.a^2+3.b \text{ [met a = -5 en b = -2]}\\&=1.(-5)^2+3.(-2)\\&=19\\ \end{align}\)
4. \(\begin{align} 3ab+4b+9&=3.a.b+4.b+9 \text{ [met a = 2 en b = -4]}\\&=3.2.(-4)+4.(-4)+9\\&=-31\\ \end{align}\)
5. \(\begin{align} 4a^2+6b&=4.a^2+6.b \text{ [met a = -5 en b = 3]}\\&=4.(-5)^2+6.3\\&=118\\ \end{align}\)
6. \(\begin{align} 3a+5b&=3.a+5.b \text{ [met a = -3 en b = -2]}\\&=3.(-3)+5.(-2)\\&=-19\\ \end{align}\)
7. \(\begin{align} 3a^2-b&=3.a^2-1.b \text{ [met a = 6 en b = -2]}\\&=3.6^2-1.(-2)\\&=110\\ \end{align}\)
8. \(\begin{align} 6a+2b&=6.a+2.b \text{ [met a = 1 en b = 5]}\\&=6.1+2.5\\&=16\\ \end{align}\)
9. \(\begin{align} 2ab-b-15&=2.a.b-1.b-15 \text{ [met a = -3 en b = 4]}\\&=2.(-3).4-1.4-15\\&=-43\\ \end{align}\)
10. \(\begin{align} 4ab+b-6&=4.a.b+1.b-6 \text{ [met a = 2 en b = 5]}\\&=4.2.5+1.5-6\\&=39\\ \end{align}\)
11. \(\begin{align} 2ab+5b-8&=2.a.b+5.b-8 \text{ [met a = 4 en b = 2]}\\&=2.4.2+5.2-8\\&=18\\ \end{align}\)
12. \(\begin{align} 10a+4b&=10.a+4.b \text{ [met a = 3 en b = 3]}\\&=10.3+4.3\\&=42\\ \end{align}\)