[질문] 근의 공식?

ax² + bx + c = 0 x² + (b/a)x + (c/a) = 0 x² + (b/a)x + (b/2a)² - (b/2a)² + (c/a) = 0............√ {x + (b/2a)}² - (b/2a)² + (c/a) = 0 {x + (b/2a