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2.09 Without actual multiplication evaluate.252 - 242. |
Answer» CORRECT QUESTION -WITHOUT actual multiplication evaluate : (Ⅰ) 25² - 24² CORRECT ANSWER -(Ⅰ) 25² - 24² = (25 + 4) (25 - 4) [applying a² - b² = (a+B)(a-b)] = (49) × (1) = 49 SOME EXPANSIONS -(Ⅰ) (a + b)² = (a² + b² + 2ab) (Ⅱ) (a - b)² = (a² + b² - 2ab) (Ⅲ) (a + b + C)² = (a² + b² + c²) 2(ab+bc+ca) (Ⅳ) (a + b)³ = a³ + b³ + 3ab(a + b) (Ⅴ) (a - b)³ = a³ - b³ - 3ab(a - b) (Ⅵ) (a² - b²) = (a + b) (a - b) |
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