Question

if x is 2 + root 5 prove that x ^2 + 1 upon x ^2 is equals 18​

Answer 1

Answer:

10-4√5

Step-by-step explanation:

x^2 = (2 +√5)^2

      =4 + 5 + 4√5

      = 9 +4√5

1 / x^2 = 1/(9+ 4√5)

         = (9-4√5) / 81- 80

          = 9-4√5

(x^2 +1) / (x^2)

= x^2/ x^2  +  1 /x^2

= 1 + 1/x^2

= 1 + 9 -4√5

= 10-4√5