急!求下列参数方程所确定的函数y的二阶导数d^2y/dx^2
求下列参数方程所确定的函数y的二阶导数d^2y/dx^2
1.x=2t-t^2, y=3t-t^3
2.x=f'(t), y=tf'(t)-f(t) (f''(t)≠0)