Question

Pls solve this question

Answer 1

Answer:

follow the steps :-

given :- a = 9 - 4root 5

squaring both sides

a² = 49 + 80 - 72 root 5

a² = 129 - 72 root 5.

1 / a = 1 / 9 - 4root 5

after rationalizing,

1/a = 9 + 4 root 5

since,

1/a² = 129 - 72 root 5

since, a² + 1 / a² = 129 - 72 root 5 + 129 + 72 root 5 .

therefore, a² + 1 / a² = 129 + 129 = 258 ans.

Step-by-step explanation:

thanks.