[填空题]
Each student in a physics:egz qpq i;7a/xkw w/o+wo39g lab is assix hiez8z lo4jpasli0,h; 1d+6gned to find the location where a bright object may be placed in order that a concave mirror wi+h,lhzjlis1o6 px z40e;a8idth radius of curvature r = 40 cm will produce an image three times the size of the object. Two students complete the assignment at different times using identical equipment, but when they compare notes later, they discover that their answers for the object distance are not the same. Explain why they do not necessarily need to repeat the lab, and justify your response with a calculation.
$d_o$ = cm cm
