Question

If x=2+√5,Prove that x2 + 1/x^2=18

Answer 1

Step-by-step explanation:

x² = 4 + 4√5 + 5 = 9+4√5

=> x²+1/x²

=> (9+4√5) + 1/(9+4√5)

=> (9+4√5) + (9-4√5)/(9²-4²√5²)

=> 9+4√5 + (9-4√5)/(81-80)

=> 9+4√5 + 9 -4√5

=> 18

Answer 2

Answer:

it is a mathematical sum and also a sum of quadritic equation s