Question

Determine whether each of the function from 𝑍 to Z is onto

(a) 𝑓(𝑛) = 𝑛³

(b) 𝑓(𝑛) = 𝑛² − 1

Answer 1

$a\,\,-\,\,no: f\left( n \right) =2\Rightarrow n^3=2-no\,\,solution\\b\,\,-\,\,no: f\left( n \right) =-2\Rightarrow n^2-1=-2-no\,\,solution$