Functions Question 668

Question: $\begin{aligned} & f(x)=\begin{cases} x, & \text { if } \mathrm{x} \text { is rational } \\ 0, & \text { if } \mathrm{x} \text { is irrational }\end{cases}, g(x) = \begin{cases}0, & \text { if } \mathrm{x} \text { is rational } \\ x, & \text { if } \mathrm{x} \text { is irrational }\end{cases} \end{aligned}$

[IIT Screening 2005]

Options:

A) One-one onto

B) One-one not onto

C) Not one-one but onto

D) Not one-one not onto

Show Answer

Answer:

Correct Answer: A

Solution:

$ (f-g)(x)= \begin{cases} & x,x\in Q \\ & -x,x\notin Q \\ \end{cases} . $