一元二次 2x^2-3x+7=0

運用二次公式解下列各方程 如有需要 答案以根式表示
2x² - 3x + 7 = 0

x = [-b ± √(b² - 4ac)] / 2a
x = {-(-3) ± √[(-3)² - 4(2)(7)]} / 2(2)
x = [3 ± √(-47)] / 4
x = (3 + i√47) / 4 或 x = (3 - i√47) / 4
（i = √-1）


根據下列各組的根 建立未知數為x的一元二次方程
3或4
-2或5

x = 3 或 x = 4
x - 3 = 0 或 x - 4 = 0
(x - 3)(x - 4) = 0
x² - 7x + 12= 0

x = -2 或 x = 5
x + 2 = 0 或 x - 5 = 0
(x + 2)(x - 5) = 0
x² - 3x - 10= 0


解下列各方程
x² + 5x + 6 = 0
(x + 2)(x + 3) = 0
x = -2 或 x = -3

2x² + 3x + 1 = 0
(2x + 1)(x + 1) = 0
x = -1/2 或 x = -1

2x² + 9x + 4 = 0
(2x + 1)(x + 4) = 0
x = -1/2 或 x = -4

(2x + 1)(x + 1) = 3
2x² + 3x + 1 = 3
2x² + 3x - 2 = 0
(2x - 1)(x + 2) = 0
x = 1/2 或 x = -2