Jawabanmu

2014-06-09T18:38:50+07:00
R=2f
f= 10 cm

1/f=1/s+1/s'
1/10 = 1/5 +1/s'
1/s' = 1/10 cm
s'=10 cm
2014-06-09T18:42:14+07:00
F=20/2
f=10

1/s1=1/10 - 1/5
=1/10 / 2/10
=1/10
s1=10cm