Correct Answer - Option 1 :
\(2\sqrt 2 - \sqrt 7 \)
Let 15 – 4√14 = a
⇒ a = 8 + 7 – (2 × 2 × √14)
⇒ a = 8 + 7 – [2 × √(22 × 14)]
⇒ a = (√8)2 + (√7)2 – (2 × √56)
⇒ a = (√8)2 + (√7)2 – (2 × √8 × √7)
⇒ a = (√8)2 – (2 × √7 × √8) + (√7)2
⇒ a = (√8 – √7)2
Taking square root on both the sides, we get:
√a = √8 – √7 = 2√2 – √7
∴ The square root of 915 – 4√14) is (2√2 – √7)