1. Решите неравенство:
a)x2 +2x-8>0; б)-2x2 -x+620, b)2x2 -5x+6 <0,

a) x² + 2x - 8 > 0

D = b² - 4ac

D = 4 - 4*1*(-8) = 4 + 32 = 36

x₁ = (-2 + √36)/2 = (-2 + 6)/2 = 4/2 = 2

x₂ = (-2 - √36)/2 = (-2 - 6)/2 = -8/2 = -4

б) -2x² - x + 6 = 0

D = b² - 4ac

D = 1 - 4*(-2)*6 = 1 + 48 = 49

x₁ = (1 + √49)/2*(-2) = (1 + 7)/(-4) = 8/(-4) = -2

x₂ = (1 - √49)/2*(-2) = (1 - 7)/2 = -8/2 = -4

b) 2x² - 5x + 6 < 0

D = 25 - 4*2*6 = -23

D < 0, нет корней