A) -1.5 D
B) -6.5 D
C) +6.6 D
D) +6.5 D
Correct Answer: A
Solution :
Power of combination is given by \[P=\frac{1}{{{f}_{1}}}+\frac{1}{{{f}_{2}}}\] Here, \[{{f}_{1}}=40\,cm=0.4\,m\] for convex, \[{{f}_{2}}=-25\,cm=0.25\,m\]for concave \[=\frac{1}{0.40}+\frac{1}{-0.25}=2.5\,D-4D=-1.5D\]
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