2w^2-7w+6=(2w-3)(w-2)
w^2-3w+1=0:w=3/2±5^0.5/2
(w+2)(w^2+2w+4)=w^3+4w^2+8w+8->2w^2+8w+8
w=1/(log2)*(logx)
cos(w)^2-sin(w)^2=cos(2w)
意味不明？