Let A= (x, y) : x>0, y>0, x2+y2=1 and let B=(x,y):x>0,y>0,x6+y6=1 Then A∩B
A
B
∅
{(0,1),(1,0)}
x6+y6=x2+y2x4−x2y2+y4, so if (x,y)A∩B then 1=x4−x2y2+y4=x2+y22−3x2y2 =1−3x2y2⇒x2y2=0 x=0 or y=0 but x>0,y>0 so A∩B=ϕ