Is y=(x/2)^2 a function?

Which graph represents the solution set for the given system of inequalities? x+2y< 3 x+y> 4 3x-2y> 4

The coordinates r(1, -3), s(3, -1) t(5, -7) form what type of polygon? a right triangle an acute triangle an equilateral triangle an obtuse triangle

If set d is not the empty set but is a subset of set e, then which of the following is true? d ∩ e = d d ∩ e = e d ∩ e = ∅