Are you, perhaps, a beginning algebra student, and you're wondering if the statements in that image are valid or faked? (You posted on the Beginning Algebra board).
Or, you are not a beginning algebra student, and you posted on the wrong board, maybe?
What you posted is not beginning algebra, and it looks like valid math. It seems to conclude that -- in some sequence of numbers -- the difference between adjacent elements is non-negative. That could also be interpreted as a conclusion that the number sequence is decreasing. :cool: