c2−25c+5. 49x2−y27x−y. 49x2−y27x+y. 9b2−13b−1. 9b2−13b+1. 16x4−25a24x2−5a. 16x4−25a24x2+5a. 9x2−25y23x−5y. a2−(b−c)2a−(b−c). a2−(b−c)2a+(b−c). a2−(2b−c)2a−(2b−c). (5a−7b)2−1(5a−7b)−1. (5a−7b)2−1(5a−7b)+1. z2−(x−y)2z−(x−y). z2−(x−y)2z+(x−y). a2−(2b−c)2a+(2b−c). (x+3y)2−z2(x+3y)−z. (x+3y)2−z2x+3y+z.