2. Substitute into the equation . So your other co-ordinate is .
3. The normal to a curve at a given point P is the straight line perpendicular to the tangent at P and passing through P. If the tangent has gradient , the gradient of the normal is .
In your example, the normal to the curve at is ; hence at . You should be able to find a from here. Once you’ve found a, substitute into to find the y-coordinate, which is b.