\(\Leftrightarrow x^3-2x^2+x^2-2x+x-2\)

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

\(\Leftrightarrow\left(x-2\right)\left(x^2+x+1\right)\)

Ai đồ giỏi Toán quasss cho em xin víaaa.

1: =(x-1-y)(x-1+y)

3: =(x-1)(x+1)(x-2)

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

\(x^3-x^2-x+1\)

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

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

\(x^3-x^2+7x-7=x^2\left(x-1\right)+7\left(x-1\right)=\left(x-1\right)\left(x^2+7\right)\)

b) \(x^2y-x^3-10y+10x\)

\(=x^2\left(y-x\right)-10\left(y-x\right)\)

\(=\left(y-x\right)\left(x^2-10\right)\)

c) \(x^2\left(x-2\right)+49\left(2-x\right)\)

\(=\left(x-2\right)\left(x^2-49\right)\)

\(=\left(x-2\right)\left(x-7\right)\left(x+7\right)\)

a, \(x^2\) + 4\(x\) - y² + 4

= (\(x^2\) + 4\(x\) + 4) - y²

= (\(x\) + 2)² - y²

= (\(x\) + 2 - y)(\(x\) + 2 + y)

b, 2\(x^2\) - 18

= 2.(\(x^2\) -9)

= 2.(\(x\) -3).(\(x\) + 3)

+ )   x 3   +   7 x 2   +   12 x   +   4     =   x 3   +   6 x 2   +   x 2   +   12 x   +   8   –   4     =   ( x 3   +   6 x 2   +   12 x   +   8 )   +   ( x 2   –   4 )     =   ( x 3   +   3 . 2 . x 2   +   3 . 2 2 . x   +   2 3 )   +   ( x 2   –   4 )     =   ( x   +   2 ) 3   +   ( x   –   2 ) ( x   +   2 )     =   ( x   +   2 ) ( ( x   +   2 ) 2   +   x   –   2 )     =   ( x   +   2 ) ( x 2   +   4 x   +   x   –   2 )     =   ( x   +   2 ) ( x 2   +   5 x   +   2 )

Đáp án cần chọn là: A

a) \(A=x^2-6x+9-9y^2\)

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

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

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

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

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

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

a, \(A=\left(x-3\right)^2-9y^2=\left(x-3-3y\right)\left(x-3+3y\right)\)

b, \(B=\left(x-1\right)^3+2\left(x-1\right)\left(x+1\right)=\left(x-1\right)\left[\left(x-1\right)^2+2\left(x+1\right)\right]\)

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