Question

If X=4-√15 then find the value of [X+1/X]

Answer 1

‡Heya!

x = 4 - √15

1/x = 1(4-√15)

            Rationalising the denominator,

1/x = 1(4-√15) × (4+√15)/(4+√15)

 = (4+√15)/(4-√15)(4+√15)

= (4+√15)/(4²-√15²)

= (4+√15)/(16-15)

= (4+√15)/1

1/x = (4+√15)

=> x+1/x = 4 - √15 + 4 + √15

 = 8

The required answer is 8.

Hope it helps..!