Question

課長ツライナー

(2)の一段目の式から2段目の式に変える仕方を教えてください

-(b+c)³+3bc (b+c)
= (b+c){(b+c)²+3a(a+b+c)-(b+c)²+3bc}
=3(b+c){a(a+b+c)+bc}
=3(b+c)(a²+ab+bc+ca)
=3(a+b)(b+c) (c+a)
(2) (5x)=(a+b)²(x²)²—2(a²+b²)x²y²+(a−b)²(y²)²
=(x²− y²){(a+b)²x² — (a−b)²y²}
=(x+y)(x−y){(a+b)x+(a−b)y}{(a+b)x−(a−b)y}
=(x+y)(x−y)(ax+bx+ay-by) (ax+bx-ay+by)
-1
(a+b)²X_(a−b)².
(a+b)²
(a - b)²
2
(5x)=(x¹—2x²y²+y¹) a² +2b(x² - y²) a+b²(x¹-2x²y²-
= (x² - y²)²a²+2ab(x² + y²)(x² − y²)+b²(x² - y²)²
= (x² - y²) {(x² - y²) a² +2ab(x²+y²)+b²(x² - y²)}
1
->
−(a+b)²
-(a−b)²
-2(a²+6²)