từng câu 1 thôi:v

a) x2-xy+5y-25
 = x(2-y)+ 5(y-2)
 = x(2-y)-5(2-y)
 = (x-5)(2-y)

h: \(=\left(a-1-b\right)\left(a-1+b\right)\)

a, x(a - b) + (a - b)

= (x + 1)(a - b)

b, x(a + b) - a - b

= x(a + b) - (a + b)

= (x - 1)(a + b)

c, 10ax - 5ay - 2x + y

=  5a(2x - y) - (2x - y)

= (5a - 1)(2x - y)

d, 2a^2x - 5by - 5a^2y + 2bx

= 2x(a^2 + b) - 5y(b + a^2)

= (2a - 5y)(a^2 + b)

làm tiếp:

2ax² - bx² - 2ax +bx +4a-2b

= x²(2a-b) - x(2a-b) +2(2a-b)

=(2a-b)(x²-x+2)

1)\(x\left(a-b\right)+a-b=x\left(a-b\right)+\left(a-b\right)=\left(a-b\right)\left(a+x\right)\)

2)\(x\left(a+b\right)-a-b=x\left(a+b\right)-\left(a+b\right)=\left(a+b\right)\left(x-1\right)\)

3)\(10ax-5ay-2x+y=\left(10ax-5ay\right)-\left(2x-y\right)=5a\left(2x-y\right)-\left(2x-y\right)=\left(2x-y\right)\left(5a-1\right)\)

4)\(2a^2x-5by-5a^2y+2bx=\left(2a^2x-5a^2y\right)+\left(2bx-5by\right)=a^2\left(2x-5y\right)+b\left(2x-5y\right)=\left(2x-5y\right)\left(a^2+b\right)\)5)\(2ax^2-bx^2-2ax+bx+4a-2b=\left(2ax^2-bx^2\right)-\left(2ax-bx\right)+\left(4a-2b\right)=x^2\left(2a-b\right)-x\left(2a-b\right)+2\left(2a-b\right)\)\(=\left(2a-b\right)\left(x^2-x+2\right)\)

\(1,=x\left(x^2-2x+1-y^2\right)=x\left[\left(x-1\right)^2-y^2\right]=x\left(x-y-1\right)\left(x+y-1\right)\\ 2,=\left(x+y\right)^3\\ 3,=\left(2y-z\right)\left(4x+7y\right)\\ 4,=\left(x+2\right)^2\\ 5,Sửa:x\left(x-2\right)-x+2=0\\ \Leftrightarrow\left(x-2\right)\left(x-1\right)=0\Leftrightarrow\left[{}\begin{matrix}x=1\\x=2\end{matrix}\right.\)

Câu 1: A

Câu 21: A

\(16,A\\ 17,C\\ 18,A\\ 19,C\\ 20,A\\ 21,A\)

1a

Đa thức này không phân tích được bạn ơi

\(2x^2y+4xy^2+2y^3-8\) 

\(=2y\left(x^2+2xy+y^2\right)-8\)

\(=2y\left(x+y\right)^2-8\) 

\(=2\left[y\left(x+y\right)^2-4\right]\)

thank you huỳnh thanh phong

\(2x^2+2y^2-4xy-xz+yz=\left(2x^2+2y^2-4xy\right)-\left(xz-yz\right)=2\left(x^2-2xy+y^2\right)-z\left(x-y\right)=2\left(x-y\right)^2-z\left(x-y\right)=\left(x-y\right)\left(2x-2y-z\right)\)

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

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

=x(x-y)-2(x-y)=(x-y)(x-2)