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Are $a, b \in \mathbb{R}, then applies (a+b)^{2} = a^{2} + ab + b^{2} $ \\ 
better \\ 
are $a, b \in \mathbb{R}, \textrm{then applies} \, (a+b)^{2 } = a^{2 } + ab + b^{2}$\\ 
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