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  1. If x4 +
    1
    = 119 ,and x > l, then the value of x3 -
    1
    is
    x4x3
    1. 54
    2. 18
    3. 72
    4. 36
Correct Option: D

Using Rule1 and 8,

x4 +
1
= 119
x4

x2 +
1
2 - 2 = 119
x2

x2 +
1
2 = 121
x2

⇒ x2 +
1
= 11
x2

x -
1
2 + 2 = 11
x

x -
1
2 = 9
x

⇒ x -
1
= 3
x

∴ x3 -
1
- 3x -
1
= 27
x3x

⇒ x3 -
1
- 3 × 3 = 27
x3

⇒ x3 -
1
= 27 + 9 = 36
x3



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