Question

if a^2+b^2+c^2=1 and ab+bc+ca=40, find a+b+c
please give answer with full formula​

Answer 1

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• a² + b² + c² = 1
• ab + bc + ca = 40
• a + b + c = ?

we know that,

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

(a + b + c)² = 1 + 2(40)

(a + b + c)² = 1 + 80

(a + b + c)² = 81

a + b + c = √81

a + b + c = 9

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