Any square must be centered at the origin. Therefore B is the image of A rotated by 90 degrees about the origin. (C and D will work themselves out.)
A=(x,x2+8x+7)
B=(-x2-8x-7,x)
but since B is also on the first parabola we can substitute this point into the first equation which simplifies into the quartic
0 = x4+16x3+70x2+47x
Which has 4 real roots:
x={0, -.8157899, -7.756981, 7.427229} |