4х²+10х-36=0
2х²+9х-5=0
3х²-2х-1=0

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Ответ:

1) Д = 100 - 4 • 4 •(-36) = 676

x1 = - 10 + 26/ 8 = 2

x2 = -10 - 26/8 = - 4,5

2) Д = 81 - 4 • 2 • (-5) = 121

x1 = - 9 + 11/ 4 = 0,5

x2 = -9 - 11/4 = - 5

3) Д = 2 - 4 • 3 • (-1) = 14

х1 = 2 + 2√3/6

х2 = 2 - 2√3/6