dx/dt= 1,dy/dt=-2t,dz/dt=3t?
At this time t= 1.
The tangent vector T=( 1,-2,3) is obtained by substitution.
2. The tangent vector pointing to the negative side of the X axis is (-1, 2, -3). Excuse me: Since X is negative, change the sign of X, why change the sign of all?
Because it points in the negative direction of the x axis.
therefore
X must be less than 0.
therefore
Tangent vector =-( 1,-2,3) = (-1,2,3)
All signs must be changed.