Jawabanmu

2014-05-21T08:32:59+07:00

a.) 1/s' = 1/f - 1/s

= 1/15 - 1/20

=1/60

s'= 60 cm

b.) M = s'/s

=60 / 20

=3 kali

NB: jng lupa f= 1/2 R