Question

$(x - 2y - z)^{2}$
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Answer 1

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$(x - 2y - z)^{2}$

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$\boxed{\red{\bold{Simply \ use \ identity:}}}$

$(x+y+z)^2 = x^2 +y^2 + z^2 + 2xy + 2yz \\ + 2zx$

$(x-2y-z)^2 = x^2 + (-2y)^2 + (-z)^2 \\ + 2(x)(-2y) + 2(-2y)(-z) +2(-z)(x)$

$(x-2y-z)^2 = x^2 + 4y^2 + z^2 -4xy +4yz\\ -2zx$

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