# Math Help - 1-1 and onto

1. ## 1-1 and onto

can we find such a function which obeys the given rules;
1.)it is defined on integer to integer,and 1-1 and onto,
2.)f(1)=-5,f(7)=17,
3.)and for all n>5,f(2n)=2n.

2. Originally Posted by sah_mat
can we find such a function which obeys the given rules;
1.)it is defined on integer to integer,and 1-1 and onto,
2.)f(1)=-5,f(7)=17,
3.)and for all n>5,f(2n)=2n.

$
f(n) = \begin{cases} -5, & n =1
\\ 1, & n =-5
\\ 17, & n=7
\\ 7,&n=17
\\ n,& {\rm{otherwise}}

\end{cases}
$