由a+2b+3c=6,可得(a+1)+(2b+1)+(3c+1)=9,∴3[(a+1)+(2b+1)+(3c+1)]=27.再利用柯西不等式,可得(1+1+1)?[(a+1)+(2b+1)+(3c+1)]=27≥( a+1 + 2b+1 + 3c+1 )2,∴ a+1 + 2b+1 + 3c+1 ≤3 3 ,当且仅当 a+1 =