Could you please explain number 2 on page 28?

Sure. I assume you’ve already read the solution in the back, which approaches this by plugging in (it is the plugging in chapter drill after all). So I’ll quickly explain *why* it has to be this way.

Note that you can combine the two given inequalities into one line: . Of course, that means we know that the inequality , without the , is also true! We can simplify that inequality! Just add to both sides to end up with all the terms on one side: