Spectacles, Focal length and Lens Formula

[ZedCar]

Homework Statement

When using the lens formula: 1/f = 1/u + 1/v

for someone who has short sightedness and cannot focus on objects on objects more than 2.5m away, I get:

1/f = 1/infinity + 1/-2.5
f = -2.5 mIf using the formula for someone who had long sightedness and could not focus on objects closer than 2.5m does this mean the equation would be:

1/f = 1/infinity + 1/2.5
f = 2.5 m

Thanks!

Homework Equations

1/f = 1/u + 1/v

The Attempt at a Solution

 

[ZedCar]

bumpity

 

[ZedCar]

Anyone?