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å
å¯å¯¼ä¸g'(0)=-1
(xâ0)limf(x)/g²(x)=2
å 为(xâ0)limg²(x)=0
å(xâ0)limf(x)=0
f(0)=0
对(xâ0)limf(x)/g²(x)=2è¿è¡åå½¢
(xâ0)limf(x)/g²(x)
=(xâ0)lim[f(x)/x][x²/g(x)]
=(xâ0)lim[f(x)/x²]•(xâ0)limx²/g(x) ï¼åæ两个æéä¹ç§¯ï¼å¹¶å¯¹å³è¾¹çæéç¨
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=(xâ0)lim[f(x)/x²]•(xâ0)limx/g(x)•(xâ0)lim1/g'(x)
=(xâ0)lim[f(x)/x²]•(-1)•(-1)
=2
å æ¤f(x)=2x²+o(x)
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å³f'(0)=0
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