第1个回答 2017-05-23
f(x)=1/x²
那么导数为f'(x)
=lim (dx趋于0) [f(x+dx) -f(x)]/dx
=lim (dx趋于0) [1/(x+dx)² -1/x²]/dx
=lim (dx趋于0) [-(2xdx+dx²)/(x+dx)²x²] /dx
=lim (dx趋于0) -(2x+dx)/(x+dx)²x²
代入dx=0，得到f'(x)= -2/x^3本回答被网友采纳
那么导数为f'(x)
=lim (dx趋于0) [f(x+dx) -f(x)]/dx
=lim (dx趋于0) [1/(x+dx)² -1/x²]/dx
=lim (dx趋于0) [-(2xdx+dx²)/(x+dx)²x²] /dx
=lim (dx趋于0) -(2x+dx)/(x+dx)²x²
代入dx=0，得到f'(x)= -2/x^3本回答被网友采纳