Calculus help please?!?! (FIND CRITICAL NUMBER)

1) Find the critical numbers of the function f(x) = (x^2 - x)^1/3

(a) 1/2
(b) 0, 1/2, and 1
(c) 0 and 1/2

i got "A", is this the correct answer?!?!

2) For what value of a is the following equation true?

limit of "x" to infinity," ((x + a) / (x - a))^x = e"



(a)1/2
(b) 2
(c)3/2

I got "A", is this correct?!?!

THANS!!

1. f(x) = (x^2 - x)^(1/3)

f'(x) = (1/3) (x^2 - x)^(-2/3) • (2x - 1) = (2x - 1)/[3(x^2 - x)^(2/3)] = 0

2x - 1 = 0, or x = 1/2

x^2 - x = x(x - 1) = 0
x = 0 or x = 1

Derivative is 0, when x = 1/2; is undefined when x = 0 or x = 1.

b

2) a