利用配方法解二次方式

2x2 - √5x - 30 = 0

2[x2 - (√5)x/2] - 30 = 0

2[x2 - 2(√5/4)x + (√5/4)2] - 2(√5/4)2 - 30 = 0

2[x - (√5/4)]2 - (25/8) - 30 = 0

[x - (√5/4)]2 - (25/16) - 15 = 0

[x - (√5/4)]2 = (265/16)

x - (√5/4) = √(265)/4 ooro x - (√5/4) = -√(265)/4

x = (√5 + √265)/4 ooro x = (√5 - √265)/4
=