GUJCET 2018 Math Solved Paper

f(n) = {

n 2 ;	n−even
−( n−1 2 );	n−odd

when n=2,4,6, 8.1....
f(n)={1,2,3.....}
when n=1,3,5...
f(n)={0,−1,−2,−3...}
∴ Function is one-one and onto

Clealy f is one-one function as for each even natural number we have different image as positive integer and for odd natural number image set is set of non-positive integer. also their are no any integer for which pre image does not exists. Henceone-one onto