Question

Разложите на множители многочлен
1) a³ - 27b³
3) x⁶ - y⁶
5) (a - b)³ + b³
7) 8a³ + (a-b)³​

Answer 1

$1) \: {a}^{3} - 27 {b}^{3} = (a - 3b)( {a}^{2} + 3ab + 9 {b}^{2} ) \\ 3) \: {x}^{6} - {y}^{6} = (x - y)( {x}^{2} + xy + {y}^{2} )(x + y)( {x}^{2} - xy + {y}^{2} ) \\ 5) \: {(a - b)}^{3} + {b}^{3} = a( {a}^{2} - 3ab + 3 {b}^{2} ) \\ 7) \: 8 {a}^{3} + {(a - b)}^{3} = (3a - b)(3 {a}^{2} + {b}^{2} )$

Answer 2

$a^3-27b^3=(a-3b)(a^2+3ab+b^2)\\\\(x^6-y^6)=(x^3-y^3)(x^3+y^3)=(x-y)(x^2+xy+y^2)(x+y)(x^2-xy+y^2)\\\\(a-b)^3+b^3=(a-b+b)((a-b)^2-b(a-b)+b^2)=a(a^2-3ab+3b^2)\\\\8a^3+(a-b)^3=(2a+a-b)(4a^2-2a(a-b)+(a-b)^2)=\\=(3a-b)(4a^2-2a^2+2ab+a^2-2ab+b^2)=(3a-b)(3a^2+b^2)$