Answer :
As it stands, it's none of those. I believe you were going for the distance formula but copied it wrong.
[tex]It's\ none\ of\ those.[/tex]
[tex]d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\Leftarrow Distance\ Formula\\\\A(x_1;\ y_1);\ B(x_2;\ y_2)\Rightarrow d=|AB|[/tex]
[tex]d=\sqrt{(x_2-x_1)^2+(y_2-y_1)^2}\Leftarrow Distance\ Formula\\\\A(x_1;\ y_1);\ B(x_2;\ y_2)\Rightarrow d=|AB|[/tex]
