Find the Required Set

Find the Required Set

Question:

If \( f:[-2,2]\to R \) is defined by

\[ f(x)= \begin{cases} -1, & -2\le x\le0 \\ x-1, & 0\le x\le2 \end{cases} \]

then

\[ \{x\in[-2,2]:x\le0 \text{ and } f(|x|)=x\} \]

is equal to

(a) \(\{-1\}\)
(b) \(\{0\}\)
(c) \(\left\{-\frac12\right\}\)
(d) \(\phi\)

Solution:

Since \(x\le0\),

\[ |x|=-x\ge0 \]

Therefore,

\[ f(|x|)=|x|-1 \]

Given,

\[ f(|x|)=x \]

\[ |x|-1=x \]

Since \(x\le0\),

\[ -x-1=x \]

\[ -1=2x \]

\[ x=-\frac12 \]

Hence,

\[ \boxed{\left\{-\frac12\right\}} \]

\[ \boxed{\text{Correct Answer: (c)}} \]

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