If a 2 + b 2 = 234 and ab = 108, find the value of (a + b) / (a - b).

We know that, (a + b)² = a² + b² + 2ab
= 234 + 2 x 108 = 450
(a - b)² = a² + b² - 2ab
= 234 - 2 x 108 = 18
∴ (a + b)²/(a - b)² = 450/18 = 25
⇒ [(a + b)/(a - b)]² = 25
∴ (a + b)/(a - b) = √25 = 5