※ 引述《JimCroce (我要下五子棋 ￾N￾ )》之铭言： : f(h) : Consider lim ---- = 1 f(x+y)=f(x)+f(y)+(x^2y)+(xy^2) : h->0 h : 任意x,y 属於实数 , find f`(x) by definition : p.s(f`(x)是对f(x)一次微分 ,抱歉打的很乱) f(x+h) - f(x) f`(x) = lim -------------- h->0 h f(x)+f(h)+(x^2h)+(xh^2) - f(x) = lim -------------------------------- h->0 h f(h)+(x^2h)+(xh^2) = lim -------------------------------- h->0 h f(h) = lim [ ---- + x^2 + xh ] h->0 h = 1 + x^2 --

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