$A$ function $f$ from the set of natural numbers $\mathbb{N}$ to the set of integers $\mathbb{Z}$ is defined by $f(n) = \begin{cases} \frac{n-1}{2}, & \text{if } n \text{ is odd} \\ -\frac{n}{2}, & \text{if } n \text{ is even} \end{cases}$. The function $f$ is:

  • A
    One-one but not onto
  • B
    Onto but not one-one
  • C
    One-one and onto both
  • D
    Neither one-one nor onto

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Similar Questions

Let $R$ denote the set of all real numbers and $R^{+}$ denote the set of all positive real numbers. For the subsets $A$ and $B$ of $R$,define $f: A \rightarrow B$ by $f(x) = x^2$ for $x \in A$. Match the items in Column-$I$ with the items in Column-$II$.
Column-$I$Column-$II$
$A$. $f$ is one-one and onto,if$1$. $A = R^{+}, B = R$
$B$. $f$ is one-one but not onto,if$2$. $A = B = R$
$C$. $f$ is onto but not one-one,if$3$. $A = R, B = R^{+}$
$D$. $f$ is neither one-one nor onto,if$4$. $A = B = R^{+}$

Consider a function $f: [0, \frac{\pi}{2}] \rightarrow \mathbb{R}$ given by $f(x) = \sin x$ and $g: [0, \frac{\pi}{2}] \rightarrow \mathbb{R}$ given by $g(x) = \cos x$. Show that $f$ and $g$ are one-one,but $f + g$ is not one-one.

The function $f: R-\{1\} \rightarrow R-\{4\}$ defined by $f(x) = \frac{4x-3}{x-1}$ for $x \in R-\{1\}$ is

$f(x) = x + \sqrt{x^2}$ is a function from $R \to R$,then $f(x)$ is

$f: N \rightarrow N$,is defined by $f(x)=x^6$ then, . . . . . . .

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