Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:
"Let f : A →B be a function. Assume there is a function g : B → A satisfying fog(x) = x then"
Options:
f is invertible
f is neither one one nor onto
f is onto but need not be one one
Nothing can be decided about f
Correct Answer:
f is onto but need not be one one
Explanation:
For showing f is onto , start with y in B and consider g(y). For one one , try to cook up some examples by taking f and g finite sets.`