9x2−19x+1=09 x^{2}-19 x+1=09x2−19x+1=0
9x2+19x−1=09 x^{2}+19 x-1=09x2+19x−1=0
9x2−19x−1=09 x^{2}-19 x-1=09x2−19x−1=0