Functions Question 102

Question: If $ f:

[0,\ \infty )\to [0,\ \infty ) $ and $ f(x)=\frac{x}{1+x}, $ then f is [IIT Screening 2003]

Options:

A) One-one and onto

B) One-one but not onto

C) Onto but not one-one

D) Neither one-one nor onto

Show Answer

Answer:

Correct Answer: B

Solution:

$ {f}’(x)=\frac{1}{{{(1+x)}^{2}}}>0,,\forall x\in [0,,\infty ) $ and range $ \in [0,,1) $
Þ function is one-one but not onto.