Lettervormen getalwaarde

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Bereken de getalwaarde

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

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Bereken de getalwaarde

Verbetersleutel

1. \(\begin{align} 2ab-2b-3&=2.a.b-2.b-3 \text{ [met a = 4 en b = -3]}\\&=2.4.(-3)-2.(-3)-3\\&=-21\\ \end{align}\)
2. \(\begin{align} 3a^2-6b&=3.a^2-6.b \text{ [met a = 2 en b = 3]}\\&=3.2^2-6.3\\&=-6\\ \end{align}\)
3. \(\begin{align} 5a-5b&=5.a-5.b \text{ [met a = 2 en b = 4]}\\&=5.2-5.4\\&=-10\\ \end{align}\)
4. \(\begin{align} 9a-2b&=9.a-2.b \text{ [met a = -1 en b = 4]}\\&=9.(-1)-2.4\\&=-17\\ \end{align}\)
5. \(\begin{align} ab+b+5&=1.a.b+1.b+5 \text{ [met a = -2 en b = 4]}\\&=1.(-2).4+1.4+5\\&=1\\ \end{align}\)
6. \(\begin{align} 7a-10b&=7.a-10.b \text{ [met a = -1 en b = 3]}\\&=7.(-1)-10.3\\&=-37\\ \end{align}\)
7. \(\begin{align} 4ab-4b+7&=4.a.b-4.b+7 \text{ [met a = 4 en b = 2]}\\&=4.4.2-4.2+7\\&=31\\ \end{align}\)
8. \(\begin{align} 4a-7b&=4.a-7.b \text{ [met a = 3 en b = 5]}\\&=4.3-7.5\\&=-23\\ \end{align}\)
9. \(\begin{align} 4ab+2b+15&=4.a.b+2.b+15 \text{ [met a = -2 en b = -5]}\\&=4.(-2).(-5)+2.(-5)+15\\&=45\\ \end{align}\)
10. \(\begin{align} a^2-6b&=1.a^2-6.b \text{ [met a = 3 en b = 6]}\\&=1.3^2-6.6\\&=-27\\ \end{align}\)
11. \(\begin{align} 2a^2-b&=2.a^2-1.b \text{ [met a = -4 en b = 1]}\\&=2.(-4)^2-1.1\\&=31\\ \end{align}\)
12. \(\begin{align} 2a+6b&=2.a+6.b \text{ [met a = 2 en b = 5]}\\&=2.2+6.5\\&=34\\ \end{align}\)