# Let A={1,2,3,....n} and B={a,b}. Then the number of surjection from A into B is \begin{array}{1 1}(A)\quad"p_2 \qquad & (B)\quad 2"-2\\ (C)\quad 2^n-1 \qquad & (D)\quad none\;of\;these\end{array}

## 1 Answer

Toolbox:
• The number of surjections from set A having n elements to set B having 2 elements is $2^n-2$
$A=\{1,2,3,......n\} \qquad B=\{a,b\}$

A has n elements B has 2 elements

number of surjection is $2^n-2$

'B' option is correct

answered Mar 5, 2013 by

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