Question

Решить уравнение a)x²-3x-4=0 б) x²-11x+18=0

Answer 1

a) x²-3x-4=0

D=9+16=25

√25=5

x1,2=(3±5)÷2

x1=-1

x2=4

Answer 2

а) Д = 3*3 - 4*(-4)*1 = 9 + 16 = 25 = 5*5

х1,2 = (3 +/- 5)/2

х1 = 4

х2 = -1

б)Д = 11*11 - 4*18*1 = 121 - 72 = 49 = 7*7

х1,2 = (11 +/- 7)/2

х1 = 9

х2 = 2