ax² + bx + c = 0
b² - 4ac
[-b ± â(b²-4ac)]/2a
(-b/2a, f(-b/2a))
x² - 9 = 0
x² + 2x + 1 = 0
2² - 8x + 6 = 0
-x² + 4x - 3 = 0