The line y = mx + 1 cuts the parabola y2=4ax at two points P and Q. If equation  of circle with diameter as PQ is x2+y2+18x+4y+5=0 then a + m equal to

by eleminating y from the givien equations mx+12=4axm2x2+2mx+1=4axm2x2+2m−4ax+1=0x−x1x−x2=x2+2xm−2am2+1m2         ......1by eleminating x from the given equations y2−4ay−1m=0y−y1y−y2=y2−4aym+4am                       ......2Add the above two equations x−x1x−x2+y−y1y−y2=x2+y2+2xm−2am2−4aym+4am+1m2=x2+y2+18x+4y+5m=13,a=−13