\(x^2+7x+12=x\left(x+3\right)+4\left(x+3\right)=\left(x+3\right)\left(x+4\right)\)

\(=x^2+3x+4x+12\)
\(=x\left(x+3\right)+4\left(x+3\right)\)
\(=\left(x+3\right)\left(x+4\right)\)

\(x^3-3x^2+1-3x=\left(x^3+1\right)-3x^2-3x\)

\(=\left(x+1\right)\left(x^2-x+1\right)-3x\left(x+1\right)=\left(x+1\right)\left(x^2-x+1-3x\right)=\left(x+1\right)\left(x^2-4x+1\right)\)

\(\dfrac{1}{4}x^2+2xy+4y^2=\left(\dfrac{1}{2}x+2y\right)^2\)

(x^2 +7x)-(y^2+7y)

=x(x+7)-y(y+7)

=(x+7)(y+7)(x-y)

Đề đúng không thế. Nếu đúng thì bài này phức tạp lắm

\(x^8+3x^3+1\)

\(=x^8-x^4+4x^4+4\)

\(=\left(x^4-1\right)\cdot\left(x^4+1\right)+4\cdot\left(x^4+1\right)\)

\(=\left(x^4+1\right)\cdot\left(x^4-1+4\right)\)

\(=\left(x^4+1\right)\cdot\left(x^4+3\right)\)

sai rồi bạn

\(x^4-5x^2y^2+4y^4\)

\(=\left(x^2\right)^2-2x^22y^2+\left(2y^2\right)^2-x^2y^2\)

\(=\left(x^2-2y^2\right)^2-\left(xy\right)^2\)

\(=\left(x^2-2y^2-xy\right)\left(x^2-2y^2+xy\right)\)

cá này là bình phương thếu.k thể phân tích thành nhân tử dc nữa

\(x-\sqrt{x}-2\\ =x+\sqrt{x}-2\sqrt{x}-2\\ =\sqrt{x}\left(\sqrt{x}+1\right)-2\left(\sqrt{x}+1\right)\\ =\left(\sqrt{x}+1\right)\left(\sqrt{x}-2\right)\)