IBPS Clerk Prelims practice question
If a + b = 14 and a - b = 6, find the value of a³ + b³.
From a IBPS Clerk Prelims Quantitative Aptitude practice set · Quantitative Aptitude
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Correct answer: (B) 1064
ab = [(a+b)² - (a-b)²]/4 = [14² - 6²]/4 = [196 - 36]/4 = 40. Then a³ + b³ = (a+b)³ - 3ab(a+b) = 14³ - 3 × 40 × 14 = 2744 - 1680 = 1064.
हिंदी में प्रश्न
यदि a + b = 14 और a - b = 6 है, तो a³ + b³ का मान ज्ञात कीजिए।
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सही उत्तर: (B) 1064
ab = [(a+b)² - (a-b)²]/4 = [14² - 6²]/4 = [196 - 36]/4 = 40। फिर a³ + b³ = (a+b)³ - 3ab(a+b) = 14³ - 3 × 40 × 14 = 2744 - 1680 = 1064।
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