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If x2 + x = 5 then the value of (x + 3)3 + 1 is (x + 3)3
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- 140
- 110
- 130
- 120
- 140
Correct Option: B
x2 + x = 5 (Given)
Let, x + 3 = a
| ∴ | = | |||
| x + 3 | a |
| Now , a + | = (x + 3) + | |||
| a | (x + 3) |
| a + | = | |||
| a | (x + 3) |
| a + | = | |||
| a | x + 3 |
| a + | = | |||
| a | x + 3 |
| a + | = | |||
| a | x + 3 |
| a + | = | = | = 5 | |||
| a | x + 3 | x + 3 |
| ∴ a3 + | = |  | a + |  | 3 | - 3 . a . | | a + | | ||||
| a3 | a | a | a |
Required answer = (5)3 – 3 × 5 = 125 – 15 = 110
