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  1. If   x = √3 + √2  then the value of   x3 −
    1
    		  is
    x3
    1. 10√2
    2. 14√2
    3. 22√2
    4. 8√2
Correct Option: C

x = √3 + √2

∴ 
1
 =
1
x√3 + √2

=
√3 − √2
(√3 + √2)(√3 − √2)

=
√3 − √2
 = √3 − √2
3 − 2

∴  x −
1
 = √3 + √2 − √3 + √2 = 2√2
x

∴  x3 −
1
 = x −
1
3 + 3 x −
1
x3xx

= (2√2)3 + 3 × 2√2
= 16√2 + 6√2 = 22√2


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