x=( 1+t)/t，x'=- 1/t？ When t= 1, x=2, x'=- 1, the tangent equation x=-(t- 1)+2=t+ 1, that is, x=-t+3.

y = t/( 1+t)= 1- 1/( 1+t)，y'= 1/(t+ 1)？ When t= 1, y= 1/2, y'= 1/4.

The tangent equation y=(t- 1)/4 +2, that is, y=t/4+7/4.

Z = 2t 2, z' = 4t, when t= 1, z=2, z'=4, the tangent equation z=4(t- 1)+2 means z=4t-2.