Advanced Graphing: Implicit Plot - Flag Real Complex root

[compsystems]

1: The following graph is called the graph of the engine, showing the rotor and the stator and rotor can spin.

Y^4-96*Y^2-X^4+100*X^2=0

http://www.wolframalpha.com/input/?i=Y%5...*X%5E2%3D0

2: The following graph (ASTROIDE) plots only in the first quadrant, but to change flag (CAS SETTINGS) use principal root no plots in all four quadrants, Why is this happening?

X^(2/3)+Y^(2/3)=16




http://www.wolframalpha.com/input/?i=X%5...a=%5E_Real

http://www.wolframalpha.com/input/?i=X%5..._Principal