Correct Answer - Option 3 : 9

**Given: **

(a + b) = 11

ab = 10

**Formula Used:**

(a + b)^{2} = a^{2} + b^{2} + 2ab

(a - b)^{2} = a2 + b2 - 2ab

**Calculation:**

Squaring both the side

(a + b)^{2} = (11)^{2}

⇒ a2 + b2 + (2 × 10) = 121

⇒ a2 + b2 = 101

(a - b)^{2} = a2 + b2 - 2ab

⇒ (a - b)2 = 101 - 2(10)

⇒ (a - b)^{2} = 81

∴ a - b = 9

The correct option is 3 i.e. 9