Let E be the ellipse x29+y24=1 and C be the circle
x2+y2=9. Let P(1, 2) and Q(2,1) be two points, then
Q lies inside C but outside E
Q lies outside both C and E
P lies inside both C and E
P lies inside C but out side E
C:x2+y2−9=0
E:x2/9+y2/4−1=0
.
For P(1, 2), C:1+4−9<0, E:19+44−1>0
So P lies outside E and inside C.
For Q(2,1),C:4+1−9<0, E:49+14−1<0
So Q lies inside both C and E.