If x - y = 1, then what is the value of x- y- 3xy?

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  2. 1
  3. 2
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Answer (Detailed Solution Below)

Option 2 : 1
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Detailed Solution

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Given:

If x - y = 1

Formula used:

x3 - y3 - 3xy = (x - y)(x2 + xy + y2) - 3xy

Calculation:

x - y = 1

⇒ x3 - y3 - 3xy = 1(x2 + xy + y2) - 3xy

⇒ x3 - y3 - 3xy = x2 + xy + y2 - 3xy

⇒ x3 - y3 - 3xy = x2 + y2 - 2xy

⇒ x3 - y3 - 3xy = (x - y)2

⇒ x3 - y3 - 3xy = 12

⇒ x3 - y3 - 3xy = 1

∴ The correct answer is option (2).

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