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  1. If x = √3 + √2 , then the value of x3 -
    1
    is :
    x3

    1. 14√2
    2. 14√3
    3. 22√2
    4. 10√2
Correct Option: C

x = √3 + √2

1
=
1
x3 + √2

=
3 - √2

( √3 + √2 )( √3 - √2 )

= √3 - √2
∴ x +
1
= √3 + √2 + √3 + √2 = 2√2
x

Cubing both sides,
x -
1
3 = 16√2
x

⇒ x3 -
1
- 3x -
1
= 16√2
x3x

⇒ x3 -
1
- 3 × 2√2 = 16√2
x3

⇒ x3 -
1
= 16√2 + 6√2 = 22√2
x3



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