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If   -3< x< -1 , then

Option: 1

-\frac{1}{3}<\frac{1}{x}<-1


Option: 2

9<x^{2}<1


Option: 3

0 \leqslant x^{2}<9


Option: 4

-1<\frac{1}{x}<-\frac{1}{3}.


Answers (1)

best_answer

Sol:-3<x<-1


As -3,-1<0 , then we can square all 3 sides and change sign of inequality


\begin{aligned} &(-3)^{2} >x^{2}>(-1)^{2} \\ \end{aligned}

\begin{aligned} \Rightarrow & 1<x^{2}<9 \end{aligned}

Also -3<x<-1
For \frac{1}{x} , we can take reciprocal of all 3 sides with change in sign of inequality


\begin{aligned} &\text { (As }-3,-1<0 \text { ) } \\ \end{aligned}

\begin{aligned} &\frac{-1}{3}>\frac{1}{x}>-1 \end{aligned}

 

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