Question

Problems Set at an Oral Examination.
Represent the following sets of points on the plane (x, y).
$\left\{\right(x,+y)||x+y|+|y-x|⩽4\}.$

Answer 1

Since all the points for $|y+x|$+ $\frac{|y-x|}{4}$ represent a region of square which thus side of $4$, we can say that the region is as given in figure.