RRB ALP practice question
If x satisfies (log10 x)2 - 3(log10 x) + 2 = 0, find the sum of all possible values of x.
From a RRB ALP Quantitative Aptitude practice set · Quantitative Aptitude
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Correct answer: (A) 110
Let t = log10 x. Then t2 - 3t + 2 = 0, i.e. (t-1)(t-2) = 0, so t = 1 or t = 2. Thus x = 10 or x = 100. Sum = 10 + 100 = 110.
हिंदी में प्रश्न
यदि x, (log10 x)2 - 3(log10 x) + 2 = 0 को संतुष्ट करता है, तो x के सभी संभावित मानों का योग ज्ञात कीजिए।
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सही उत्तर: (A) 110
मान लीजिए t = log10 x। तब t2 - 3t + 2 = 0, अर्थात (t-1)(t-2) = 0, अतः t = 1 या t = 2। इस प्रकार x = 10 या x = 100। योग = 10 + 100 = 110।
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