I'm an adult learner of maths (self-studying). I've been struggling with this question and would like some help. I've been given 4 different x,y coordinates (indicated as stars on the image below) and have been asked to identify which out of those 4 coordinates signifies a negative average rate of change. Something very easy for most of you I'm sure. It doesn't make sense to me how a set of x,y coordinates constitute an interval? Any help, links to learning resources would be much appreciated.
Which set of x,y coordinates is correct and why?
1 Answer
$\begingroup$The four choices, $(-9,-8), (-9,-3)$ and so on, are not $(x,y)$ coordinates, but open intervals $(x_1,x_2)$ on the $x$-axis. Perhaps you are used to the notation $]x_1,x_2[$ for an open interval, but it means the same thing.
Does that help?
$\endgroup$ 2
