The image of an object placed on the principal axis of a concave mirror of focal length 12 cm is formed at a point which is 10 cm more distance from the mirror than the object. The magnification of the image is

1-x+1-x-10=-112 or          1x+1x+10=112 or          x+10+xxx+10=112 or         2x+10x2+10x=112 or         x2+10x=24x+120 or         x2-14x-120=0             x2-20x+6x-120=0 or        xx-20+6x-20=0            x+6x-20=0 Here  u = -20 cm ν=-20+10cm=-30 cm then  magnification m = - vu=--30-20=-1.5