Sebuah benda berasa 15cm di deoan cermin cekung, jika jarak fokus lensa 5cm, Maka bayangan adalah.....cm

1/si = 1/5-1/15
1/si = 3/15-1/15
1/si = 2/15
si = 15/2 = 7,5 cm

Diketahui =
So = 15 cm
F = 5 cm

Ditanya =
Si = ... cm

Jawab =
1/Si = 1/F - 1/So
1/Si = 1/5 cm - 1/15 cm > 1/5 × 3/3 = 3/15
1/Si = 3/15 - 1/15
1/Si = 2/15
Si = 15 ÷ 2
Si = 7,5 cm

Semoga membantu ^_^
Jadikan jawaban tercerdas yaa :D