Phân tích đa thức thành nhân tử: a(b + c)^2(b - c) + b(c + a)^2(c - a) + c(a + b)
Phân tích đa thức thành nhân tử:
a(b + c)2(b – c) + b(c + a)2(c – a) + c(a + b)2(a – b).
a(b + c)2(b – c) + b(c + a)2(c – a) + c(a + b)2(a – b)
= a(b + c)2(b – c) – b(c + a)2(b – c – b + a) + c(a + b)2(a – b)
= a(b + c)2(b – c) – b(c + a)2(b – c) – b(c + a)2(a – b) + c(a + b)2(a – b)
= (b – c)[a(b + c)2 – b(c + a)2] – (a – b)[b(c + a)2 – c(a + b)2]
= (b – c)(ab2 + ac2 + 2abc – bc2 – ba2 – 2abc) – (a – b)(bc2 + ba2 + 2abc – ca2 – cb2 – 2abc)
= (b – c)(ab2 + ac2 – bc2 – ba2) – (a – b)(bc2 + ba2 – ca2 – cb2)
= (b – c)[ab(b – a) + c2(a – b)] – (a – b)[bc(c – b) + a2(b – c)]
= (b – c)(a – b)(c2 – ab) – (a – b)(b – c)(a2 – bc)
= (a – b)(b – c)(c2 – ab – a2 + bc)
= (a – b)(b – c)[(c – a)(c + a) + b(c – a)]
= (a – b)(b – c)(c – a)(a + b + c).