CAT Practice : Functions

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When will we have an invertible function ?

Invertible Functions

    Q.21: If . Find the value of x for which f(x) = f-1(x)?
    1. -3
    2. 2
    3. Both A and B
    4. None of these


  • Correct Answer
    Choice C. Both A and B

Detailed Solution

f(x) = f-1(x) when f(x) = x
=) = x
=) x + 6 = x2 + 2x
=) x2 + x – 6 = 0
=) (x+3) (x-2) = 0
=) x = -3, 2
Answer choice (C).

Correct Answer: Both A and B

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