Answer :

crisforp
F1P - F2P = k ;
F1P = [tex] \sqrt{ (-8-8)^{2} + (0-30)^{2} } = \sqrt{64 + 900} = \sqrt{964} = 31.04;[/tex]
F2P = [tex] \sqrt{ (8-8)^{2} + (0-30)^{2} } = \sqrt{900} = 30;[/tex]
31.04 - 31 = 0.04 => k = 0.04 ;