※ 引述《simcity2013 (ONLY THE STRONG SURVIVE)》之铭言：
: 若xf(x^2)=ln(x^4+1),则f'(1)=?
: 我想问的是答案只给1-(1/2)ln2
: 难道没有-1+(1/2)ln2吗 ??
: 谢谢!!
f(1) = ln2
f(x^2) + 2x^2 f'(x^2) = 4x^3/[x^4 + 1]
=> f(1) + 2 f'(1) = 2
=> f'(1) = 1 - f(1)/2
= 1 - (1/2)ln2