Equation of parabola ⇒y2+Ay+Bx+C=0 Passes through (−2,1)(1,2) and (−1,3) y2+Ay+Bx+C=0 At (−2,1)⇒1+A−2B+C=0 At (1,2)⇒4+2A+B+C=0 At (−1,3)⇒9+3A−B+C=0 3+A+3B=0 5+A−2B=0 B=
2
5
A=−
21
5
and C=4 y2−
21
5
y+
2x
5
+4=0 (y−
21
10
)2+(
2
5
)x+(4)=0 As, y coordinate of focus will be same as y coordinate of vertex. ∴