X1 = -2
x2 = -4
a(x-x1)(x-x2)
a(x+2)(x+4)
a<0 так как ветви вниз<br>a(x²+6x+8)
ax²+6ax+8a=ax²+bx+c
b=6a
c=8a
Xв = -b/2a = -6a/2a = -3
Yв = a((-3)²+6*(-3)+8) = 1
Yв = a(9 - 18 + 8) = 1
Yв = -a = 1 => a = -1
ax²+bx+c
b = 6a
c = 8a
a = -1
-x² - 6x - 8 = 0
Проверка
-x² - 6x - 8 = 0
D = 36 - 4*(-1)(-8) = 36 - 32 = 4
x1,2 = (6 ± 2)/(-2) = -4 -2
Xв = 6/-2 = -3
Yв = -9 + 18 - 8 = 1
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