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Mathematics

If a2 + b2 + c2 = 50 and ab + bc + ca = 47, find a + b + c.

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Answer

By formula,

(a + b + c)2 = a2 + b2 + c2 + 2(ab + bc + ca).

Substituting values we get :

⇒ (a + b + c)2 = 50 + 2 × 47

⇒ (a + b + c)2 = 50 + 94

⇒ (a + b + c)2 = 144

⇒ (a + b + c) = 144=±12\sqrt{144} = \pm 12.

Hence, (a + b + c) = ±12\pm 12.

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