Question

ПОМОГИТЕ СРОЧНОООООО

Answer 1

Ответ:

Объяснение:

1.

а) 3х² - 4х -15 = 0

a=3  b = -4  c = - 15

D = b² - 4ac = (-4) ² - 4 * 3*(-15) = 16 +12*15 = 16+180 = 196 >0  

б) х²-2х+3=0

D = b² - 4ac = 4 -4*1*3 = 4-12 = -8 < 0  

в) 2х²+9х+5=0

D = b² - 4ac = 81 - 4*2*5 = 81 - 40 =40  >0  

2.  a) 5х²+14х-3 = 0

D = b² - 4ac = 196 +60 = 256

x₁₂ = (-b±√D)/2a

x₁ = (-14+16)/10 = 0,2

x₂ = (-14-16)/10 = -3

б) 2х² - 1= 0

D = b² - 4ac = 8

x₁₂ =± √D/2a

x₁ = - 2√2/4 = - √2/2

x₂  = 2√2/4 =  √2/2

в) х² = 5х-4

х² - 5х + 4 = 0

D = b² - 4ac = 25 -20 = 4

x₁₂ = (-b±√D)/2a

x₁ = (5+2)/2 = 3,5

x₂ = (5-2)/2 = 1,5