問題
(a+b)(b+2c)(2c+a)+2abc
カッコの部分をa中心に並べる.
=(b+2c)(a+)(a+2)+2abc
=(b+2c){a2+(b+2c)a+2bc}+2abc
=(b+2c)a2+(+c)2a+2bc(b2c)+2abc
=(b+2c)a2+{(b2c)2+bc}a+2bc(b2c)
たすきがけ
(b+2c) 2bc =2b
×
1 (b+2c) =(b2c)2
———————————————————————————————
(b2c)2+2c
={(b2c)a+2b}{+(b2c)}
=(b+2c+2bc)(a+b2c)
=(a+b2c)(ab+2b+2a)
(x-y)(-y+z)(z+x)-xyz
x中心にカッコをまとめる
=(-y+z)(x-)(x+z)-xyz
=(-y+z){x2+(y+z)xyz}-xyz
=(-yz)x2+(-yz)2x-y(-y+z)-xyz
=(y+z)x2+{(-y+z)2yz}x-yz(y+z)
たすきがけ
(-y+z) -yz =yz
×
1 (-y+z) =(y+z)2
———————————————————————————————
(-y+z)2yz
={(y+z)x-y}{x+(y+z)}
=(xy+zxyz)(xy+z)
=(xy+z)(xy-y+x)
お疲れ様でした。「採点」ボタンを押して採点してください。