23^3 + a3^2 +b3 + 30 = 0
2(-1)^3 + a*(-1)^2 +b*(-1) + 30 = 0
54 +9a + 3b + 30 = 0
-2 +a - b + 30 = 0
9a + 3b = - 84
a - b = -28 / * 3
9a + 3b = - 84
3a - 3b = - 84
12a = - 168 : 12
a = - 14
b = a + 28 = -14 + 28 = 14
Odp. a = -14 oraz b = 14
b)
W(x) = 2 x^3 -14 x^2 + 14x + 30
(x -3)*(x + 1) = x^2 -2x -3
W(x): x^2 -2x - 3
2x -10 stąd x = 5