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AP EAMCET · Maths · Functions

If f:AB and g:BC are two functions such that gof:AC is a bijection, then which one of the following is always true?

  1. A f and g are bijections
  2. B f is an injection and g is a surjection
  3. C f is a surjection and g is an injection
  4. D f is a bijection but g is not a bijection
Verified Solution

Answer & Solution

Correct Answer

(B) f is an injection and g is a surjection

Step-by-step Solution

Detailed explanation

Given: f:A→B and g:B→C And, gof:A→C is a bijection. Let x, y∈A such that fx=fy. Then, fx=fy ⇒gfx=gfy ⇒gofx=gofy ⇒x=y;   ∵gof:A→C is one-one Hence, fx is an injection. Now, Let z be an arbitrary…