(x-1)(x+2)=12x��+x-2-12=0x��+x-14=0x��+x+1/4=1/4+14=1/4+56/4=57/4(x+1/2)��=57/4x=-1/2+(√57)/2或2-1/2-(√57)/2
希望能解决您的问题.