Question

I can't think of any function to prove f:ZxZ -> Z defined by f(x,y)=x(x+1)y/2. help!

Answer 1

What exactly are you trying to prove?

Answer 2

Are you trying to show this function is integer valued? Or something else?

Answer 3

im trying to prove that this function is surjective

Answer 4

That's straightforward, as f(1,y) = y.

Answer 5

Hence for any integer \( y \), the element \( (1,y) \) in the domain has image \( y \). That is
\[ f(1,y) = \frac{1(1+1)y}{2} = y \]

Answer 6

i was thinking too hard.. thanks!