4 votes 4 votes How to test whether function is onto and one-to-one when function is in two variables? Determine whether below function $f:Z\,X\,Z\rightarrow\,Z$ is one-to-one, or onto or none? (a)$f(m,n)=2m-n$ (b)$f(m,n)=m^2-n^2$ Set Theory & Algebra kenneth-rosen discrete-mathematics set-theory&algebra functions + – Ayush Upadhyaya asked Sep 25, 2018 • edited Mar 4, 2019 by Pooja Khatri Ayush Upadhyaya 594 views answer comment Share Follow See all 5 Comments See all 5 5 Comments reply Show 2 previous comments srestha commented Sep 25, 2018 reply Follow Share yes 1st one is one to one and onto 2nd one is not onto and many to one https://math.stackexchange.com/questions/4467/how-to-prove-if-a-b-in-mathbb-n-then-a1-b-is-an-integer-or-an-irratio 0 votes 0 votes Mk Utkarsh commented Sep 25, 2018 reply Follow Share 1st is not one to one check my comment 1 votes 1 votes srestha commented Sep 26, 2018 reply Follow Share ok, yes thanks that means, 2 numbers subtraction or addition or multiplication or division cannot be one to one 0 votes 0 votes Please log in or register to add a comment.