Find the third derivative of f left parenthesis x right parenthesis equals 3 fourth root of x cubed end root minus 5 cos x. f apostrophe apostrophe apostrophe left parenthesis x right parenthesis equals short dash fraction numerator 45 over denominator 64 x to the power of begin display style 9 over 4 end style end exponent end fraction minus 5 sin x f apostrophe apostrophe apostrophe left parenthesis x right parenthesis equals fraction numerator 45 over denominator 4 x to the power of begin display style 9 over 4 end style end exponent end fraction minus 5 sin x f apostrophe apostrophe apostrophe left parenthesis x right parenthesis equals short dash fraction numerator 45 over denominator 4 x to the power of begin display style 9 over 4 end style end exponent end fraction plus 5 sin x f apostrophe apostrophe apostrophe left parenthesis x right parenthesis equals fraction numerator 45 over denominator 64 x to the power of begin display style 9 over 4 end style end exponent end fraction minus 5 sin x