I agree. You should always check any answers you get.

Consider this:

A rectangle is 3 cm longer than it is wide. It has an area of 40 cm^2.

So, let the width be x => the length is x + 3 => the area is x(x + 3)

So answers may appear than are not solutions (unless you want to make a new topic in maths with 'negative lengths'

)

Bob