Let [tex]\mathbf u\in\mathbb R^2[/tex], where
[tex]\mathbf u=(u_1,u_2)[/tex]
and let [tex]k\in\mathbb R[/tex] be any real constant.
Given this definition of scalar multiplication, we can see right away that there is no identity element [tex]e[/tex] such that
[tex]e\mathbf u=\mathbf u[/tex]
because
[tex]e\mathbf u=e(u_1,u_2)=(eu_1,0)\neq(u_1,u_2)=\mathbf u[/tex]