[tex]A = (6,-1) \ \rightarrow \ \ x_{A}=6, \ \ y_{A} = -1\\B = (4,3) \ \ \ \rightarrow \ \ x_{B} = 4, \ \ y_{B} = 3\\\\|AB| = \sqrt{(x_{B}-x_{A})^{2}+(y_{B}-y_{A})^{2}}}\\\\\\|AB| = \sqrt{(4-6)^{2}+((3-(-1))^{2}}} = \sqrt{(-2)^{2}+4^{2}} = \sqrt{4+16} = \sqrt{20} = \sqrt{4\cdot5} =\\=\boxed{2\sqrt{5}}[/tex]
