Question

(3a-7b-c)^2 plz do this with expanding using the identity​

Answer 1

Answer:

We are aware of the identity that

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

So

(3a - 7b - c)²

= (3a)² + (-7b)² +(- c)² + 2×3 a×(-7b) + 2×(-7b)×(-c) + 2×(-c)×3a

= 9a² + 49b² + c² - 42ab + 14bc - 6ca

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