15x^2 - 4x - 35 = 0
D = b^2 - 4*a*c = -4^2 - 4*15*(-35) = 16+2100 = 2116
VD = V2116 = 46
x1 = (4-46)/2*15 = -42/30 = -1 i 12/30 = -1 i 4/10 = -1 i 2/5
x2 = (4+46)/2*15 = 50/30 = 5/3 = 1 i 2/3
OTBET: x=-1 i 2/5 i x=1 i 2/3
