Question

If x=2+√5,prove that x² + 1/x² =28

Answer 1

Step-by-step explanation:

x=2+√5

so, x²=(2+√5)²

x²=4+5+4√5

x²=9+4√5

and the value of 1/x²=1/9+4√5

1/x²=1(9-4√5)/(9+4√5)(9-4√5)

1/x²=(9-4√5)/(81-80)

1/x²=9-4√5

so, x²+1/x²=9+4√5+9-4√5

x²+1/x²=18

so, x²+1/x²≠28

x²+1/x²=18

hope it will help you!!!!

Answer 2

hopefully it will help you