Question

a+b+c = 9
ab + bc + ca = 23
Find a2 + b2 + c2 = ?

Answer 1

Answer:

18

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Answer 2

Answer:

$( {a}^{2} + {b}^{2} + {c}^{2}) = ab + bc + ca + 2ab + 2bc + 2ca \\ ( {a + b + c)}^{2} = ab + bc +ca + 2ab + 2bc + 2ca \\ {9}^{2} = 23 + 2(ab + bc + ca) \\ 81 = 25(ab + bc + ca) \\ 3.24 = {a}^{2} + {b}^{2} + {c}^{2}$