1,\(4\cdot b^2c^2-\left(b^2+c^2-a^2\right)^2\)
2,\(\left(ax+by\right)^2-\left(ay+by\right)^2\)
3,\(\left(a^2+b^2-5\right)^2-4\left(2x+3y+1\right)^2\)
4,\(\left(4x^2-3x-18\right)^2-\left(4x^2+3x\right)^2\)
5,\(9\left(x+y-1\right)^2-4\left(2x+3y+1\right)^2\)
2, ( ax+by)2-(ax+by)2
=0