Jawabanmu

2014-05-03T20:49:26+07:00
1/f=1/s'+1/s
1/f=1/40+1/25
1/f=5/200+8/200
1/f=13/200
f=200/13

p=1/f
p=13/200
2014-05-03T21:00:37+07:00
S=25 cm
s ' =  40

1/f= 1/s + 1/s'
   = 1/25 + 1/40
   = 16+10/400
   = 26/400 = 13/200
f= 200/13 = 15,38

p=100/f (karena cm) = 100/15,38 = 6,50 dioptri