TA CÚ D = 25 CM, D’ = - OCV = - 100 CM, F = DD’/(D + D’) = 25(-100)/(25 – 100) = 100/3 CM

9.

Đỏp ỏn D. Ta cú d = 25 cm, d’ = - OC

v

= - 100 cm, f = dd’/(d + d’) = 25(-100)/(25 – 100) = 100/3

cm.