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प्रश्न
If a2 + b2 + c2 = 16 and ab + bc + ca = 10, find the value of a + b + c.
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उत्तर
We know that,
`(a + b + c)^2 = a^2 + b^2 + c^2 + 2(ab + bc + ca)`
`=> (a + b + c)^2 = 16 + 2(10)` [`∵ a^2 + b^2 + c^2 = 16` and ab + bc + ca = 10]
`=> (a + b + c)^2 = 16 + 20`
`=> (a + b + c) = sqrt36`
`=> a + b + c = +-6`
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