例1.解方程6x²-x-15=0
解：x₁+x₂=1/6，x₁·x₂=-15/6，
设x₁=1/12+u，x₂=1/12-u，(u>=0)
(1/12+u)(1/12-u)=-15/6
1/144-u²=-15/6
u²=361/144
u=19/12
x₁=5/3，x₂=-3/2.
解：x₁+x₂=1/6，x₁·x₂=-15/6，
设x₁=1/12+u，x₂=1/12-u，(u>=0)
(1/12+u)(1/12-u)=-15/6
1/144-u²=-15/6
u²=361/144
u=19/12
x₁=5/3，x₂=-3/2.
