1.b-a=(2-(1-t),t-(1-t),t-1)化简=(1+t,2t-1,t-1)所以!b-a!=[(1+t)^2+(2t-1)^2+(t-1)^2]^0.5=(6t^2 -5t+3)^0.5关于(6t^2 -5t+3),我们可以用导数求解设y=6t^2 -5t+3y'=12t-5,令12t-5=0 解得t=5/12因为00所以y=f(x)的...