f==sin(2*x^2)/2
f'=2*x*cos(2*x^2);
f'(根号下pai/x）=(2*pi*cos((2*pi^2)/x^2))/x没看懂.....不是吧！汗~f(x)=定积分上限为x^2,积分结果：f=sin(2*x^2)/2；对f求导：f'=2*x*cos(2*x^2);要求f'(根号下pai/x）=？将根号下pai/x代入f‘表达式，结果：f'(根号下pai/x）=(2*pi*cos((2*pi^2)/x^2))/x