(1)设y=y(x)由方程ey+6xy+x2-1=0确定,求y’’(0). (2)设y=y(x)是由exy-x+y-2=0确定的隐函数,求y’’(0).

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问题 (1)设y=y(x)由方程ey+6xy+x2-1=0确定,求y’’(0).
(2)设y=y(x)是由exy-x+y-2=0确定的隐函数,求y’’(0).

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答案(1)将x=0代入得y=0, ey+6xy+x2-1=0两边对x求导得ey[*]+2x=0, 将x=0,y=0代入得y’(0)=0. ey[*]+2x=0两边再对x求导得 ey[*]+2=0, 将x=0,y=0,y’(0)=0代入得y’’(0)=-2. (2)当x=0时,y=1, exy-x+y-2=0两边对x求导得 exy(y+xy’)-1+y’=0,解得y’(0)=0; exy(y+xy’)-1+y’=0两边对x求导得 exy(y+xy’)2+exy(2y’+xy’’)+y’’=0,解得y’’(0)=-1.

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