Jawabanmu

2014-05-25T18:23:08+07:00
S = 8 cm
f = 12 cm
s' =?

1/f = 1/s + 1/s'
1/12=1/8 + 1/s'
1/12 - 1/8 = 1/s'
1/s' = - 1/24
s' = 24 cm

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