solutions of simple polynomial equations not exact



Hello,

im new to maxima and can't find out how to 'force' maxima finding/printing the 
exact solutions of:

a: x^2=2*y$; 
b: y^2=x/2$;

This is -among others- what I tried:

solve([a,b],[x,y]), realonly:true;
[[x=1.259921095381759,y=0.79370052770449],[x=0,y=0]]

As the equations are simple, I (still) expect that maxima is capable of 
calculating exact solutions... - but how?

Any answers or hints?

Henning