Lettervormen getalwaarde

Bereken de getalwaarde

\(3ab+4b+5\text{ [met a = 4 en b = -5]}\)

\(\begin{align} 3ab+4b+5&=3.a.b+4.b+5 \text{ [met a = 4 en b = -5]}\\&=3.4.(-5)+4.(-5)+5\\&=-75\\ \end{align}\)