Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Relations and Functions

Question:

"Consider the function f : R - { 2 / 3 } → R defined as f(x)= 4x + 3 / 6x - 4 which of the following is true about f "

Options:

f is one one but not onto

f is onto but not one one

f is neither one one nor onto

fof(x) = x

Correct Answer:

fof(x) = x

Explanation:

$f(x)=\frac{4x + 3}{6x - 4}$

so $fof(x)=f(f(x))=\frac{4(\frac{4x + 3}{6x - 4})+3}{6(\frac{4x + 3}{6x - 4})-4}$

$=\frac{16x+12+18x-12}{24x+18-24x+16}$

$=x$