Question

NEED HELP ASAP I'm completely lost!

f(x) = ( 20)/(x^2 + 21 )

(1)Find f'(x) =

(2)Find f''(x) =

(3)Find the open interval(s) where the function is increasing:

(4)Find the open interval(s) where the function is decreasing:

(5)Find the open interval(s) where the function is concave up:

(6)Find the open interval(s) where the function is concave down:

Answer 1

it can also be written as
\\[f(x)=20*(x^2+21)^{-1}\]

Answer 2

now differentiate it

Answer 3

\[f'(x)=20*(-1)*(x^2+21)*2x\]