Question

If x =root5 + 2
Then find x2 - 1/x2

Answer 1

Answer:

x=√5+2

1/x=1/√5+2*√5-2/√5-2

= √5-2/(√5)*√5-2*2

= √5-2/5-4

= √5-2/1

1/x2=(√5-2)2

= 5-4√5+4

= 9-4√5

x2-1/x2=(9+4√5)-(9-4√5)

= 9+4√5-9+4√5

= 8√5