№2

x = (-b +/- \sqrt{D})/2a

x = 1 +/- 3i

b = -1

a = 1/2

D = b^2 - 4ac = = -3

D = 1 -2c = -3

c = 2

Ответ: 1/2*x^2 - x + 2 = 0

№3

(2+i)x - (1-i)y = 1 + 3i

2x + ix -y + iy = 1 + 3i

(2x-y) + (x+y)i = 1 + 3i