A tangent to the parabola `y^2 + 4bx =0` meet, the parabola `y^2 = 4ax` in P and Q. Then t locus of midpoint of PQ is.

A tangent to the parabola y^2 + 4bx = 0 meets the parabola y^2 = 4ax in P and Q. The locus of the middle points of PQ is:

A variable tangent to the parabola y^(2)=4ax meets the parabola y^(2)=-4ax P and Q. The locus of the mid-point of PQ, is

A variable tangent to the parabola y^(2)=4ax meets the parabola y^(2)=-4ax P and Q. The locus of the mid-point of PQ, is

The tangent at the point P(x_(1),y_(1)) to the parabola y^(2)=4ax meets the parabola y^(2)=4a(x+b) at Q and R .the coordinates of the mid-point of QR are

A tangent to the parabola y^(2)=4ax meets axes at A and B .Then the locus of mid-point of line AB is