a/ \(x^4-5x^2+4=x^4-4x^2+2^2-x^2\)
\(=\left(x^2-2\right)^2-x^2\)
\(=\left(x^2-2-x\right)\left(x^2-2+x\right)\)
\(=\left(x^2-x-2\right)\left(x^2+x+2\right)\)
b/ sửa đề: \(\left(x+y+z\right)^3-x^3-y^3-z^3\)
Tìm trong câu hỏi tt có nhé bn!
\(\left(x+y+z\right)^3-x^3-y^3-z^3\\ =x^3+y^3+z^3+3\left(x+y\right)\left(y+z\right)\left(x+z\right)-x^3-y^3-z^3\\ =3\left(x+y\right)\left(y+z\right)\left(x+z\right)\)
a, x4 - 5x2 + 4
= x4 - 4x2 + 22 - x2
= (x2 - 2)2 -x2
= ( x2 - 2 - x) ( x2 - 2 + x)
= ( x2 - x - 2) ( x2 + x + 2)
