b: \(x^2-2xy+y^2-z^2\)

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

\(=\left(x-y-z\right)\left(x-y+z\right)\)

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

\(1,\\ a,=\left(x-y\right)^2-z^2=\left(x-y-z\right)\left(x-y+z\right)\\ b,=a^2\left(a-x\right)-y\left(a-x\right)=\left(a^2-y\right)\left(a-x\right)\\ c,=\left(x-y\right)^2-z\left(x-y\right)=\left(x-y\right)\left(x-y-z\right)\\ d,=x\left(x-2y\right)+t\left(x-2y\right)=\left(x+t\right)\left(x-2y\right)\\ 2,\\ \Rightarrow x^2-4x+4-x^2+9=6\\ \Rightarrow-4x=-7\Rightarrow x=\dfrac{7}{4}\\ 3,\\ a,x^2+2x+2=\left(x+1\right)^2+1\ge1>0\\ b,-x^2+4x-5=-\left(x-2\right)^2-1\le-1< 0\)

bạn giải lại giúp mình bài 2 được ko ạ

\(2\left(x+5\right)-x^2-5x\)

\(=2\left(x+5\right)-x\left(x+5\right)\)

\(=\left(x+5\right)\left(2-x\right)\)

\(y^2-6y+9-z^2\)

\(=\left(y-3\right)^2-z^2\)

\(=\left(y-3-z\right)\left(y-3+z\right)\)

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

Chọn D

a 3  –  a 2 x – ay + xy = ( a 3  –  a 2 x) – (ay – xy)

=  a 2 (a – x) – y(a – x) = (a – x)( a 2  – y)

a; \(x^4+2x^3+10x^2-20x\)

\(=x\cdot x^3+x\cdot2x^2+x\cdot10x-x\cdot20\)

\(=x\left(x^3+2x^2+10x-20\right)\)

b: \(x^3-x^2y-xy^2+y^3\)

\(=\left(x^3+y^3\right)-xy\left(x+y\right)\)

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

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

c: \(x^5+x^3-x^2-1\)

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

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