Question

Use the formula to multiply:

(8) (9 + n) (n – 3)

Answer 1

As (x + a) (x + b) = x² + (a + b)x + ab
So, (9 + n) (n – 3) = (n + 9) (n – 3)
= n² + [9 + (–3)]n – 27
= n² + 6n – 27

∴ (9 + n) (n – 3) = n² + 6n – 27