X+ 1/2

B (2,3) x = 2 y = 3 Substitute into ellipse x? +y？ /2-a？ & gt=0

4+9/2 >=a^2

s^2<； = 17/2，(a & gt0)，0 & lta & lt=√34/2

The range of real number A is √ 6/2.