Найти второй корень уравнения и свободный член "с"

Ответ
3x^2 - 8x + c = 0
x1=4 =>
3*4^2 - 8*4 + c = 0
c = 32-48 = -16 =>
3x^2 - 8x - 16 = 0
x(1.2) = [8 +- V{8^2 - 4*3*(-16)}]/2*3 = [8 +- V{64+192}]/6 = (8 +- V256)/6 = (8 +- 16)/6
x1 = (8+16)/6 = 4
x2 = (8-16)/6 = -8/6 = -4/3