To explain the non-existence of limit at [math]x=a[/math] through the [math]\varepsilon[/math]-[math]\delta[/math] approach.[br][br]Instruction:[br][*] Check the 2nd box to show the [math]\varepsilon[/math]-challenge, and use the vertical slider to adjust your choice.[br][*] Check the 1st box to show the values of the neighbourhood [math](a-\delta,a+\delta)\setminus \{a\}[/math] under [math]g[/math], and use the horizontal slider to adjust.