Discussion

Explanation:

x = $\frac{7}{\sqrt{11-6\sqrt{2}}}$ = $\frac{7}{3-\sqrt{2}}$ = $\frac{7}{3-\sqrt{2}}$ × $\frac{3+\sqrt{2}}{3+\sqrt{2}}$ = 3 + √2

⇒ x - 3 = √2   ...(1)

⇒ (x - 3)³ = (√2)³

⇒ x³ - 27 - 9x² + 27x = 2√2

⇒ x³ - 27 - 9x² + 27x = 2(x - 3) [from (1)]

⇒ x³ - 21 - 9x² + 25x = 0

⇒ x³ - 9x² + 25x - 20 = 1

Hence, option (b).

» Your doubt will be displayed only after approval.