An clectric field is given by \( E_{x}=2 x^{3} \) i N/C. The potential of the point \( (1,-2) \), if potential of the point \( (2,4) \) is taken as zero, is
(1) \( -7.5 \times 10^{3} \mathrm{~V} \)
(2) \( 7,5 \times 10^{*} \mathrm{~V} \)
(3) \( -15 \times 10^{3} \mathrm{~V} \)
(4) \( 15 \times 10^{3} \mathrm{~V} \)