(Not even specialists -- 2nd-3rd year undergraduates in engineering/math/physics!) In that case the word 'trivial' means it doesn't require complex machinery t

(Not even specialists -- 2nd-3rd year undergraduates in engineering/math/physics!) In that case the word 'trivial' means it doesn't require complex machinery to solve. A simple consequence of arithmetic manipulations, say, may be extremely difficult to think of yourself, but once you know it it's trivial to see the validity of. I believe that counts as 'trivial' in mathematical terminology.