Jawabanmu

2014-04-23T22:04:51+07:00
Dik:s'=20 cm, f=10 cm
dit: s=...?
jb:
rumus= 1/-f=1/s+1/s'
1/s=1/-f -1/s'
=1/-10 -1/20
=-2-1 /20
=-3/20