If (27x3 - 343y3) ÷ (3x - 7y) = Ax2 + By2 + 7Cyx, then the value of (4A - B + 5C) is:
Show answer & explanation
Correct answer: C
Explanation
Correct Answer is option 3 i.e. 2
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Concept |
Application |
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Formula: a3 - b3 = (a - b) (a2 + b2 + ab) |
[27x3 – 343y3] ÷ (3x – 7y) = Ax2 + 7Cxy + By2 ⇒ [(3x)3 – (7y)3] ÷ (3x – 7y) = Ax2 + 7Cxy + By2 Using the formula: ⇒ [3x – 7y] [(3x)2 + (7y)2 + (3x) × (7y)] ÷ (3x – 7y) = Ax2 + 7Cxy + By2 ⇒ [9x2 + 21xy + 49y2] = Ax2 + 7Cxy + By2 Comparing the coefficients: ⇒ A = 9, C = 3 and B = 49 Hence, 4A – B + 5C = 36 – 49 + 15 = 2 |