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\(B=\left(a^2+b^2\right)^3+\left(c^2-a^2\right)^3-\left(b^2+c^2\right)^3\)
\(=\left(a^2+b^2+c^2-a^2\right)\left[\left(a^2+b^2\right)^2-\left(c^2-a^2\right)\left(a^2+b^2\right)+\left(c^2-a^2\right)^2\right]-\left(b^2+c^2\right)^2\)
\(=\left(b^2+c^2\right)\left[\left(a^2+b^2\right)^2-\left(c^2-a^2\right)\left(a^2+b^2\right)+\left(c^2-a^2\right)^2\right]-\left(b^2+c^2\right)^2\)
\(=\left(b^2+c^2\right)\left(a^4+2a^2b^2+b^4-a^2c^2+a^4-b^2c^2+a^2b^2-b^4-2b^2c^2-c^4\right)\)
\(=\left(b^2+c^2\right)\left(2a^4-c^4+3a^2b^2-a^2c^2-3b^2c^2\right)\)
ko chắc
\(a^3-b^3+3a^2+3ab+b^2\)
\(=\left(a-b\right)\left(a^2+ab+b^2\right)+3\left(a^2+ab+b^2\right)\)
\(=\left(a-b+3\right)\left(a^2+ab+b^2\right)\)
Phân tích đa thức sau thành nhân tử :
\(a^3\left(b-c\right)+b^3\left(c-a\right)+c^3\left(a-b\right)\)
\(a^3\left(b-c\right)+b^3\left(c-a\right)+c^3\left(a-b\right)=a^3\left(b-c\right)+b^3c-b^3a+c^3a-c^3b\\ \)
\(\Rightarrow\)\(a^3\left(b-c\right)+bc\left(b^2-c^2\right)-a\left(b^3-c^3\right)\)
\(\Rightarrow\)\(a^3\left(b-c\right)+bc\left(b-c\right)\left(b+c\right)-a\left(b-c\right)\left(b^2+bc+c^2\right)\)
\(\Rightarrow\)\(\left(b-c\right)\left(a^3+bc\left(b+c\right)-a\left(b^2+bc+c^2\right)\right)\)
\(\Rightarrow\)\(\left(b-c\right)\left(a^3+b^2c+bc^2-ab^2-abc-ac^2\right)\)
\(\Rightarrow\)\(\left(b-c\right)\left(bc\left(c-a\right)+b^2\left(c-a\right)-a\left(c^2-a^2\right)\right)\)
\(\Rightarrow\)\(\left(b-c\right)\left(c-a\right)\left(bc+b^2-a\left(c+a\right)\right)\)
\(\Rightarrow\)\(\left(b-c\right)\left(c-a\right)\left(bc+b^2-ac-a^2\right)\)
\(\left(b-c\right)\left(c-a\right)\left(b^2-a^2+c\left(b-a\right)\right)=\left(b-c\right)\left(c-a\right)\left(b-a\right)\left(a+b+c\right)\)
câu a đặt chung x ra là xong
câu b
x^3 + 3x^2 - 7x^2 - 21x + 9x+ 27 còn lại tự làm nhé
a) x3 - 2x2 + x - xy2
= x (x2 - 2x + 1 - y2)
= x [(x2 - 2x + 1) - y2]
= x [(x - 1)2 - y2]
= x [(x - 1) + y] [(x - 1) - y]
= x (x - 1 + y) (x - 1 - y)
b) x3 - 4x2 - 12x + 27
= (x3 + 27) - (4x2 + 12x)
= (x3 + 33) - 4x (x + 3)
= (x + 3) (x2 - 3x + 32) - 4x (x + 3)
= (x + 3) [(x2 - 3x + 9) - 4x]
= (x + 3) (x2 - 3x + 9 - 4x)
= (x + 3) (x2 - 7x + 9)
#Học tôt!!!
~NTTH~
c) a3 – b3 + 2b – 2a = (a – b)(a2 + ab + b2) – 2(a – b)
=(a – b)( a2 + ab + b2 – 2)