The sum of the squares of three numbers is 138, while the sum of their products taken two at a time is 131. Their sum is-
Solution
Correct Answer: Option A
মনে করি, সংখ্যা তিনটি যথাক্রমে a, b, c
প্রশ্নমতে, a2 + b2 + c2 = 138..(i)
এবং ab + bc + ca = 131(ii)
আমরা জানি,
(a+b+c)2 = (a2+b2+c2) + 2(ab + bc+ca)
=138 + 2.132
=138 +262
⇒(a+b+c)2 = 400
⇒ (a + b + c)2 = (20)2
⇒ a + b + c = 20
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