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If x = a + 2 , then the value of x2 − y2 is : y a − 2 x2 + y2
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4a a2 + 2 -
2a a2 + 2 -
4a a2 + 4 -
2a a2 + 4
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Correct Option: C
| = | ||
| y | a − 2 |
On squaring both sides,
| = | ||
| y2 | (a − 2)2 |
By componendo and dividendo,
| = | ||
| x2 + y2 | (a + 2)2 + (a − 2)2 |
| ⇒ | = | ||
| x2 + y2 | 4(a2 + 4) |
| = | |
| a2 + 4 |
[∵ (a + b)2 + (a – b)2 = 2(a2 + b2);
(a + b)2 – (a – b)2 = 4ab]
