let f(x)=(2x-pi) ^3 +2x-cosx. the value of modulus of d/dx of f inverse of x when x= pi is

after doing d{f^-1(x)}/dx we get  -6/(2x-pie)⁴ -1/2x² +1/sinx; after putting x=pie , we get   mode of  d{f^-1(x)}/dx= infinite.                                                                                 PLZ APPROVE MY ANSWER