144r^4 – 625q^2 (12r^2-25q)(12r^2+25q) (2r^2-25q)(2r^2+25q) (12r^2-5q)(12r^2+5q) (12r-25q)(12r+25q) 169c^8 – 400d^{16} (13c-20d^4)(13c+20d^4) (3c^8-20d^4)(3c^8+20d^4) (13c^8-20d^4)(13c^8+20d^4) (13c^4-20d^8)(13c^4+20d^8) :