因为a-b=3/5因为b-c=3/5两式相加a-c=6/25所以(a-c)^2=36/25………………(1)因为a-b=b-c=3/5所以(a-b)^2=9/25……………(2)同理(b-c)^2=9/25……………(3)由(1)+(2)+(3)得(a-c)^2+(b-c)^2+(a-b)^2=36/25+9/25+9/25a^2...