Find the critical numbers of the function. (Enter your answers as a comma-separated list. If an answer does not exist, enter DNE.)

f(x)=x^(4/5)(x − 6)^2

1 answer

by the product rule ....

f ' (x) = x^(4/5) (2)(x-6) + (4/5)x^(-1/5) (x-6)^2
= (-1/5)x^(-1/5) (x-6) [10x + 4(x-6) ]
= (-2/5)x^(-1/5) (x-6) (7x-12)

= 0 for critical numbers (max,min)

-1/5x^(-1/5) = 0 ---> no solution
x-6 = 0 ---> x = 6
7x-12=0 ---> x = 12/7

take it from there