Die 2.Ableitung in der Frage hatte ich übersehen
f ´ ( x ) = (-x) / √ ( 1-x2 )
f ´ ( x ) = - x / √ ( 1-x2 )
Quotientenregel
( u / v ) ´ = ( u´ * v - u * v´ ) / v^2
u = x
u ´ = 1
v = √ ( 1-x2 )
v ´ = (-x) / √ ( 1-x2 )
v^2 = ( 1 - x^2 )
f ´´ ( x ) = - [ 1 * √ ( 1-x2 ) - x * (-x) / √ ( 1-x2 ) ] / ( 1 - x^2 )
zusammenfassen
f ´´ ( x ) = - [ √ ( 1-x2 ) + x^2 / √ ( 1-x2 ) ] / ( 1 - x^2 )
f ´´ ( x ) = - [ ( ( 1-x2 ) + x^2 ) / √ ( 1-x2 ) ] / ( 1 - x^2 )
f ´´ ( x ) = - [ 1 / √ ( 1-x2 ) ] / ( 1 - x^2 )
f ´´ ( x ) = - 1 / ( √ ( 1-x2 ) * ( 1 - x^2 ) )
f ´´ ( x ) = - 1 / √ ( 1 - x2 )^3