Question

If x=(4-√15) find the value of (x+1/x)

Answer 1

x+1/x=(4-15^1/2)+(1/4-15^1/2)
rationalising denominator in second term,we get self in term as (4+15^1/2)/16-15=4+15^1/2
therefore,
x+1/x=(4-15^1/2)+(4+15^1/2)
         =4+4=8
x+1/x=8

Answer 2

Answer:

8

Step-by-step explanation:

x = 4+√15  (Given)

To find = x + 1/x

Thus,

1/x= 1/(4+√15) = 4 -√15

Solving the equation on both the sides -

1/x= 1/(4+√15) ×( 4 -√15)/ 4 -√15

1/x = 4 -√15/ 16-15

1/x = 4 -√15

x+1/x = (4+√15 + 4 - √15 )

x+1/x = 8

Therefore, the value of x+1/x will be 8.