Relations and Functions
NCERT Class 12
CBSE
Grade 12
Question:
If $f(x) = \dfrac{x - 1}{x + 1}$, $x
eq -1$, then $f(f(x))$ is equal to:
(a) $-\dfrac{1}{x}$
(b) $\dfrac{1}{x}$
(c) $-x$
(d) $x$
Step-by-Step Solution
$f(f(x)) = \dfrac{(x-1) - (x+1)}{(x-1) + (x+1)} = \dfrac{-2}{2x} = -\dfrac{1}{x}$. [1.0 Mark]
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🎯 Official CBSE Marking Scheme:
Evaluating $f(f(x)) = -1/x$: 1.0 Mark
Correct Answer: $-\dfrac{1}{x}$
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