AP Police Constable practice question
The prices of three items u, v and w add up to Rs 21, and the sum of the products of their prices taken two at a time is Rs² 68. Find u²+v²+w² (in Rs²).
From a AP Police Constable Quantitative Aptitude practice set · Quantitative Aptitude
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Correct answer: (D) 305
Using the identity (a+b+c)2 = a2+b2+c2 + 2(ab+bc+ca):
Given a+b+c = 21 and ab+bc+ca = 68.
(21)2 = a2+b2+c2 + 2(68)
441 = a2+b2+c2 + 136
a2+b2+c2 = 441 - 136 = 305.
Given a+b+c = 21 and ab+bc+ca = 68.
(21)2 = a2+b2+c2 + 2(68)
441 = a2+b2+c2 + 136
a2+b2+c2 = 441 - 136 = 305.
हिंदी में प्रश्न
तीन वस्तुओं u, v और w के मूल्यों का योग 21 रुपये है, तथा दो-दो मूल्यों के गुणनफलों का योग 68 रुपये² है। u²+v²+w² (रुपये² में) ज्ञात कीजिए।
उत्तर जाँचने के लिए किसी विकल्प पर टैप करें।
उत्तर और व्याख्या देखें
सही उत्तर: (D) 305
सर्वसमिका (a+b+c)2 = a2+b2+c2 + 2(ab+bc+ca) का प्रयोग करने पर:
दिया है a+b+c = 21 और ab+bc+ca = 68।
(21)2 = a2+b2+c2 + 2(68)
441 = a2+b2+c2 + 136
a2+b2+c2 = 441 - 136 = 305।
दिया है a+b+c = 21 और ab+bc+ca = 68।
(21)2 = a2+b2+c2 + 2(68)
441 = a2+b2+c2 + 136
a2+b2+c2 = 441 - 136 = 305।
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