20
15
15
ๅฟ็จ ๆฌกใฎๅผใๅ ๆฐๅ่งฃใใใ
ไพ้ก
3
่งฃ
a(b2-c)+b(c-aยฒ)+c(aยฒ-62)
่งฃ่ชฌ ใใฎๅผใฏ, a, b, c ใฎใฉใฎๆๅญใซใคใใฆใ2ๆฌกๅผใงใใใ ใใ
ใง,ไพใใฐ, a ใซใคใใฆ้ในใใฎ้ ใซๆด็ใใใ
a(b2-c2)+b(c-aยฒ)+c(a-b2)
=(-b+c)aยฒ+(62-cยฒ)a+(bcยฒ-b2c)
=-(b-c)aยฒ+(b+c)(b-ca-bc (b-c)
=-(b-c){aยฒ-(b+c)a+bc}
=-(b-c)(a-b) (a-c)
=(a-b) (b-c)(c-a)