По виета :
1)
x1+x2 = -B
-2 + x2 = 2a
x2 = 2a+2
2)
x1 * x2 = C
-2(2a+2) = a^2
-4a - 4 = a^2
a^2 + 4a + 4 = 0
(a+2)^2 = 0
a = -2
ответ : -2
