If x - y = 4 and xy = 45, then the value of x3 - y3 is?
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 604
| Understanding | Application |
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Tricks
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Given x - y = 4 x2 - 2xy + y2 = 16 (squaring both sides) ⇒ x2 - 2 × 45 + y2 = 16 ⇒ x2 + y2 = 16 + 90 ⇒ x2 + y2 = 106 |
| Now |
We know x3 - y3 = (x - y)(x2 + xy + y2) = 4(106 + 45) = 4 × 151 = 604 |