Question

${a}^{2} + {b}^{2} + {c}^{2} - ab + 2ab + 2bc - 2ca$
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Answer 1

Given : ${a}^{2} + {b}^{2} + {c}^{2} - ab + 2ab + 2bc - 2ca$

$= {a}^{2} + {b}^{2} + {c}^{2} + ab + 2bc - 2ca$

$= {a}^{2} + {b}^{2} + {c}^{2} + 2ab + 2bc - 2ac$

$= {a}^{2} + {b}^{2} + {c}^{2} + 2bc - 2ac$