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The sum of squares of three numbers is 138, while sum of their products taken two at a time is 131. Their sum is:1. 162. 203. 244. 26 |
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Answer» Correct Answer - Option 2 : 20 Given: The sum of squares of three numbers is 138, while sum of their products taken two at a time is 131. Concept used: (x + y + z)2 = x2 + y2 + z2 + 2(xy +yz + zx) Calculation: Let three numbers be x, y, z. The sum of squares of three numbers is 138 ⇒ x2 + y2 + z2 = 138 Sum of their products taken two at a time is 131 ⇒ xy + yz + zx = 131 Applying the formulae ⇒ (x + y + z)2 = 138 + 2(131) ⇒ (x + y + z)2 = 138 + 262 ⇒ (x + y + z)2 = 400 ⇒ x + y + z = √400 ⇒ x + y + z = 20 ∴ The sum of three numbers is 20. |
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