原式=4a2-4a(b+c)+(b+c)2+(c-b)2=4a2-4ab-4ac+2b2+2c2∵ a-b=2,a-c=1∴b=a-2 c=a-1原式=4a2-4a(a-2)-4a(a-1)+2(a-2)2+2(a-1)2=8a-4a2+4a+2a2-8a+8+2a2-4a+2=10(字母后面的2为平方)