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If 2x + 1 = 3, then the value of x3 + 1 + 2 is x x3
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3 4 -
4 5 -
5 8 -
7 8
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Correct Option: D
| 2x + | = 3 | |
| x |
On dividing by 2,
| x + | = | ||
| x | 2 |
On cubing both sides,
 | x + |  | 3 | = | | | 3 | ||
| x | 2 |
| ⇒ x3 + | + 3 | | x + | | = | |||
| x3 | x | 8 |
| ⇒ x3 + | + 3 × | = | |||
| x3 | 2 | 8 |
| ⇒ x3 + | + | = | |||
| x3 | 2 | 8 |
| ⇒ x3 + | = | − | |||
| x3 | 8 | 2 |
| = | = | ||
| 8 | 8 |
| ∴ x3 + | + 2 | |
| x3 |
| = 2 − | = | ||
| 8 | 8 |
| = | |
| 8 |
