Find the extreme value of the following function y = x ^ 4-8x ^ 3 + 18 ^ 2-1

Find the extreme value of the following function y = x ^ 4-8x ^ 3 + 18 ^ 2-1

Derivation of y = x ^ 4-8x ^ 3 + 18x ^ 2-1
Let the derivative be equal to zero
The abscissa X of the extreme point can be obtained
Then we can get the value of extreme value y from the equation
Derivative of y = 4x ^ 3-24x ^ 2 + 36x = 4x (x ^ 2-6x + 9) = 4x (x-3) ^ 2 = 0
We get x = 0 or x = 3
When x = 0, y = - 1
When x = 3, y = 26
So the extreme values are - 1 and 26