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Question
If f(x) = |x|, prove that fof = f.
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Solution
If f(x) = |x|, prove that fof = f.
(fof) (x) = f (f (x)) = f (|x|) = | |x| | = |x| = f (x)
So,
(fof) (x) = f (x), ∀x ∈ R
Hence, fof = f
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