Question

The local minimum of the cubic function:
y= -1/3x^3 + 6x^2 - 27x - 9
is found when x=?

Answer 1

take the derivative, set it equal to zero and solve

Answer 2

this is a cubic with negative leading coefficient, so it looks like

Answer 3

local min therefore is located when \(x\) is the smaller of the two zeros. the larger of the two will be give the local max

Answer 4

x=-2.25

Answer 5

-x^2+12x-27 = 0
-x^2+12x=27
-x^2+x=27/-12
x=-2.25

Answer 6

right?