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Question
a2 + b2 + c2 = 42, ab + bc + ac = 29 ∴ a + b + c = ______.
Options
16
14
12
10
MCQ
Fill in the Blanks
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Solution
a2 + b2 + c2 = 42, ab + bc + ac = 29 ∴ a + b + c = 10.
Explanation:
(a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ac)
(a + b + c)2 = 42 + 2(29)
(a + b + c)2 = 42 + 58
(a + b + c)2 = 100
∴ a + b + c = `sqrt100`
∴ a + b + c = 10
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