Question

Use the formula to multiply:

(2) (b + 2) (b – 1)

Answer 1

As (x + a) (x + b) = x² + (a + b)x + ab

So, (b + 2) (b – 1) = b² + (2 – 1)b – 2
= b² + b – 2
∴ (b + 2) (b – 1) = b² + b – 2