CBSE BoardEnglish MediumSTD 11 ScienceMathsModel Paper 102 Marks
Question
Is $B =\left\{ x : x ^2+2 x +1=0, x \in N \right\}$ a singleton set?
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Answer
We have, $B=\left\{x: x^2+2 x+1=0, x \in N\right]$ Now, $x^2+2 x+1=0$ $\Rightarrow(x+1)^2=0$ $\Rightarrow x=-1$ which is not a natural number. Thus. $B =\{ \}=\phi$ Hence, B is not a singleton set.
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