x2= 11 + 2√30 হলে, x + 1/x এর মান কত?

দেয়া আছে, 
x² = 11 + 2√30
x² = 6 + 2√30  + 5
x² = (√6)² + 2.√6.√5 + (√5)²
x² = (√6 +√5)²
x = √6 +√5 
1/x = 1/(√6 +√5)
1/x = (√6 - √5)/(√6 +√5)(√6 -√5)
1/x = (√6 - √5)/(√6)² - (√5)²
1/x = (√6 - √5)/(6 - 5)
1/x = √6 - √5

x  + 1/x = √6 + √5 + √6 - √5 = 2√6