设函数y=x^4-8x^2,则 d^2y/dx^2=?

设函数y=x^4-8x^2,则 d^2y/dx^2=? 设函数y=sin(2x²+1),求dy/dx,d²y/dx² 设函数y=y(x)由x=1-e^t和y=t+e^-t确定,求dy/dx和d^2y/dx^2 设y=y(x)是由方程xy+e^y=y+1所确定的隐函数,求d^2y/dx^2 x=0 设函数y=y(x)由方程y=xe^y确定,求dy/dx和d^2/dx^2 设DX=4,DY=2且X与Y独立,则D（3X-2Y）=? 设y=x+siny,则[(d^2)y]/[dx^2]=? 设函数y=y(x)由方程x^2y^2+y=1(y>0)所确定 求dy/dx|x=0,d^2y/dx^2|x=0. 设函数y=y(x)由方程y+e^(x+y)=2x确定,求dx/dy 设参数函数x=ln(1+t^2),y=t-arctant.求(d^2y)/(dx^2). 设参数方程x=t-In(1+t^2) y=arctant 确定函数y=y(x),求d^2y/dx^2 设由方程x+2y+z=e^(x-y-z)确定的隐函数为z=z(x,y),求d^2z/dx^2