Given, P=+5D
We have,
‌ Power, ‌P‌=‌

1

f(‌ in meter ‌)

+5‌=‌

1

f

f‌=‌

1

5

m
‌=‌

100

5

=20‌cm
Focal length, f=20‌cm(or+20‌cm ).
Since, focal length of the lens is positive.
Therefore, the nature of lens is convex.
Same size and inverted image is formed when
Magnification, m=−1
Also,
m‌=‌

v

u

v‌=−u
From the lens formula,
‌

1

v

−‌

1

u

=‌

1

f

−‌

1

u

+‌

1

u

‌=‌

1

f

‌

−2

u

‌=‌

1

f

u‌=−2f
u‌=−2×20‌‌[∵f=20‌cm]
‌=−40‌cm.