速写人物眉毛的画法:求因式分解

来源:百度文库 编辑:神马品牌网 时间:2024/05/09 06:03:33
a+b+c-ab-bc-ac+abc-1

a+b+c-ab-bc-ac+abc-1
=(abc-ab+c-1)+(a+b-bc-ac)
=(ab+1)(c-1)+[a(1-c)+b(1-c)]
=(ab+1)(c-1)-(c-1)(a+b)
=(c-1)(ab-a-b+1)
=(a-1)(b-1)(c-1)

a+b+c-ab-bc-ac+abc-1
=(abc-ab)-(ac-a)+(c-1)+(b-bc)
=ab(c-1)-a(c-1)+(c-1)-b(c-1)
=(ab-a-b+1)(c-1)
=(a-1)(b-1)(c-1)

令a=1得:a+b+c-ab-bc-ac+abc-1=0
说明a-1是它的因式
同理可知b-1,c-1也是它的因式.
又因为最高次项abc只有三次
所以结果是(a-1)(b-1)(c-1)
展开验算正确

解:原式=(abc-ab+c-1)+(a+b-bc-ac)
=(ab+1)(c-1)+[a*(1-c)+b(1-c)]
=(ab+1)(c-1)-(c-1)(a+b)
=(c-1)(ab-a-b+1)
=(a-1)(b-1)(c-1)

答题完毕

楼上正确