Question

expand the following using suitable identity: (3a-7b-c)^2​

Answer 1

Step-by-step explanation:

$using \: formula : \\ {(a - b - c)}^{2} = {a}^{2} + {b}^{2} + {c}^{2} - 2ab + 2bc - 2ca \\ {(3a - 7b - c)}^{2} = {(3a)}^{2} + {(7b)}^{2} + {(c)}^{2} - 2 \times 3a \times 7b + 2 \times 7b \times c - 2 \times c \times 3a \\ = 9 {a}^{2} + 49 {b}^{2} + {c}^{2} - 42ab + 14bc - 6ca$

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