6x²-x-12=06x²-x=12 两边同时乘1/6x²-x/6=2 x²-x/6+(1/12)²=2+(1/12)²(x-1/12)²=289/144x-1/12=±√(289/144)x-1/12=±17/12x-1/12=17/12 或 x-1/12=-17/12x1=3/2x2=-4/3