y = 5 + 6x + x^3
y ' = 6 + 3x^2
y' = 0
6+3x^2 = 0
x^2 = -2
x = +/-sqrt(2)i
- + -
-----------------'--------------'----------->
-sqrt(2)i sqrt(2)i
- точка максимума
y = 5 + 6x + x^3
y ' = 6 + 3x^2
y' = 0
6+3x^2 = 0
x^2 = -2
x = +/-sqrt(2)i
- + -
-----------------'--------------'----------->
-sqrt(2)i sqrt(2)i