配方法：t+1/6t-1/3=0 (t+1/6t+1/144)=1/3+1/144 (t+1/12)=49/144 等号两边同时开方得：t+1/12=±7/12 解得：t=7/12-1/12=1/2或t=-7/12-1/12=-2/3