Hi,

2) You have 2 values of t that gives y=9 : t=0 and t=6

The 2 corresponding points are A(0,9) and B(√(6),9)

Derivation of x gives 1/(2√(t)). It is infinite for t=0 and 1/(2√(6)) for t=6.

Derivation of y gives 2(t-3). It gives -6 for t=0 and 6 for t=6.

Therefore the tangent in A is parallel to x axis

The tangent in B has a vector (1/(2√(6) , 6) that can give you the equation of the tangent (I let you finish the job)