Shape and Colour matching:
Linkage games:
Hidden object:
Third person character control:
Single character control:
Multiple character control:
Construction:
Others:
... the expression to the left of "=", that will make it a perfect square trinomial of the form x2 + 2xy + y2. Since "2xy" in this case is (b/a)x, we must have y = b/(2a), so ...