a-2b＝2,则2a－4b＝();1/2a-b＝()

(1) 2b=(c+b)-(c-b) =(3a2-6a+3)-(a2-2a+3) =2a2-4a， c=[(c+b)+(c-b)]/2 =[(3a2-6a+3)+(a2-2a+3)]/2 =2a2-4a+3. ∴2b-c =(2a2-4a)-(2a2-4a+3) =-3. (2) c=2a2-4a+3 =2(a-1)2+1. ∴a=1时，c最小值为1. (3) c/b=(2a2-4a+3)/(a2-2a) =2+[3/a(a-2)] ∴3/a(a-2)为整