⇒‌‌2√x2+y2+4x+4=(x+8) Squaring on both sides;
4x2+4y2+16x+16=x2+64+16x
⇒3x2+4y2=48, which is equation of an ellipse given (y=3),∵(x,3) lies on an ellipse. ⇒‌‌3x2+4×9=48 ⇒‌‌3x2=12 ⇒‌‌x2=4 (here we take only positive value of x. ) ⇒‌x=±2 ⇒‌x=2