What is the positive difference between 8 and 9

In a graph with several intervals o data how does a constant interval appear? what type of scenario produces a constant interval?

Hi, can anyone show me how to do this problem? 100 points for this. in advance

Parabolas y=−2x^2 and y=2x^2 +k intersect at points a and b that are in the third and the fourth quadrants respectively. find k if length of the segment ab is 5.