(d^2)y/d(x^2)不就是y關(guān)于x的二階導(dǎo)數(shù)嘛,還化什么簡?!
由條件x=2t-1得t=(x+1)/2.帶入te^y+y+1=0得：(x+1)e^y+2y+2=0
所以,上式兩邊對x求導(dǎo)化簡得：e^y+[(x+1)e^y+2]dy/dx=0.再次在等式兩邊對x求導(dǎo)化簡得：[(x+1)e^y+2]*(d^2)y/d(x^2)+(x+1)e^(2y)(dy/dx)^2+2e^y(dy/dx)=0.
當(dāng)t=0時,帶回條件知x=-1,y=-1.
將所得帶入e^y+[(x+1)e^y+2]dy/dx=0求得：dy/dx=-1/(2e).再將所得全部帶入[(x+1)e^y+2]*(d^2)y/d(x^2)+(x+1)e^(2y)(dy/dx)^2+2e^y(dy/dx)=0中就有：
(d^2)y/d(x^2)=e^(y-1)/2
即：當(dāng)t=0時,(d^2)y/d(x^2)=e^(y-1)/2.