Question

Find all of the critical numbers for the function f(x) = x^3 – 8x^2 + 11x + 20

Answer 1

critical numbers eh.... no interval to worry about?

Answer 2

f'(x) gives us some good numbers...

Answer 3

f'(x) = 3x^2 -16x +11

now make this equal to zero to determine our critical numbers...

Answer 4

16 +- sqrt(16^2 -(4)(11)(3))
-------------------------
2(3)

Answer 5

16 +- 2sqrt(31)
------------- if I did it right
6

Answer 6

you should have an inflection point at -16/6 thats critical as well

Answer 7

Okay I understand now, you used the quadratc equation,right?