Question

найдите корни квадратного трехчлена 

 

а)3х2 - 2х - 8 = 

 

б) 6х2 + 5х - 4 =

 

в) -х + 4х - 3 =

Answer 1

а)3х2 - 2х - 8 = 3(x-2)(x+4/3) = (x-2)(3x + 4)
   D1 = 1 + 24 = 25
x1 = (1+5)/3= 2
x2 = (1-5)/3 =-4/3
б) 6х2 + 5х - 4 = 6(x-1/2)(x+4/3) = (2x-1)(3x+4)
D = 25 + 96 = 121
x1 =(-5+11)/12 = 1/2
x2 = (-5-11)/12 = -4/3
в) -х + 4х - 3 =-(x-1)(x-3)
D1 = 4 - 3 = 1
x1 = -(-2+1) = 1
x2 = -(-2-1) = 3