Lettervormen getalwaarde

Bereken de getalwaarde

\(3ab-2b+8\text{ [met a = -1 en b = 5]}\)

\(\begin{align} 3ab-2b+8&=3.a.b-2.b+8 \text{ [met a = -1 en b = 5]}\\&=3.(-1).5-2.5+8\\&=-17\\ \end{align}\)