Equation of tangent to parabola `x^2 = 4ay`

Equation of tangent to parabola y^(2)=4ax

Equation of tangent to the parabola y^(2)=16x at P(3,6) is

The equation of tangent to the parabola y^(2)=9x, which pass through the point (4,10) is

The equation of a tangent to the parabola y^(2)=8x is y=x+2. The point on this line from which the other tangent to the parabola is perpendicular to the given tangent is

The equation of a tangent to the parabola y^(2)=12x is 2y+x+12=0. The point on this line such that the other tangent to the parabola is perpendicular to the given tangent is (a,b) then |a+b|=