Question

${ \times 2 + \times + 1 = 0}^{?}$
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Answer 1

$\it x^2+x+1=0 \Rightarrow x^2+x+\dfrac{1}{4}+\dfrac{3}{4}=\underbrace{\Big(x+\dfrac{1}{2}\Big)^2+\dfrac{3}{4}}_{>0}=0 \Rightarrow x\not\in\mathbb{R}$