Lettervormen getalwaarde

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Bereken de getalwaarde

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

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Bereken de getalwaarde

Verbetersleutel

1. \(\begin{align} 3ab-3b-6&=3.a.b-3.b-6 \text{ [met a = 1 en b = 5]}\\&=3.1.5-3.5-6\\&=-6\\ \end{align}\)
2. \(\begin{align} 3a-8b&=3.a-8.b \text{ [met a = -1 en b = -4]}\\&=3.(-1)-8.(-4)\\&=29\\ \end{align}\)
3. \(\begin{align} a^2+6b&=1.a^2+6.b \text{ [met a = 2 en b = 5]}\\&=1.2^2+6.5\\&=34\\ \end{align}\)
4. \(\begin{align} 5ab-b+5&=5.a.b-1.b+5 \text{ [met a = 1 en b = 4]}\\&=5.1.4-1.4+5\\&=21\\ \end{align}\)
5. \(\begin{align} 7a+2b&=7.a+2.b \text{ [met a = -3 en b = -2]}\\&=7.(-3)+2.(-2)\\&=-25\\ \end{align}\)
6. \(\begin{align} a^2-5b&=1.a^2-5.b \text{ [met a = 2 en b = 6]}\\&=1.2^2-5.6\\&=-26\\ \end{align}\)
7. \(\begin{align} 3a-7b&=3.a-7.b \text{ [met a = -2 en b = -4]}\\&=3.(-2)-7.(-4)\\&=22\\ \end{align}\)
8. \(\begin{align} 3a^2+2b&=3.a^2+2.b \text{ [met a = -4 en b = 6]}\\&=3.(-4)^2+2.6\\&=60\\ \end{align}\)
9. \(\begin{align} 5a-3b&=5.a-3.b \text{ [met a = -1 en b = 2]}\\&=5.(-1)-3.2\\&=-11\\ \end{align}\)
10. \(\begin{align} 3a^2-6b&=3.a^2-6.b \text{ [met a = 5 en b = 3]}\\&=3.5^2-6.3\\&=57\\ \end{align}\)
11. \(\begin{align} 2a^2-3b&=2.a^2-3.b \text{ [met a = -2 en b = -5]}\\&=2.(-2)^2-3.(-5)\\&=23\\ \end{align}\)
12. \(\begin{align} 4a-4b&=4.a-4.b \text{ [met a = -4 en b = 5]}\\&=4.(-4)-4.5\\&=-36\\ \end{align}\)