\(=\left(x-y\right)\left(x+y\right)-10\left(x+y\right)=\)

\(=\left(x+y\right)\left(x-y-10\right)\)

= (x - y). (x + y) - 10 ( x - y)

= [( x + y) - 10)] . ( x - y)

  \(x^2\) - y² - 10\(x\) - 10y 

= (\(x^2\) - y²) - 10.(\(x\) + y)

= (\(x-y\))(\(x\) + y) - 10.(\(x\) + y)

= (\(x\) + y).(\(x\) - y - 10)

Bạn xem lại đề

`#3107.101107`

`x^2 - y^2 + 10x - 10y`

`= (x^2 - y^2) + (10x - 10y)`

`= (x - y)(x + y) + 10(x - y)`

`= (x + y + 10)(x - y)`

_____

Sử dụng HĐT:

`A^2 - B^2 = (A - B)(A + B).`

\(x^2-xy-10x+10y\)

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

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

\(5\left(x-1\right)^2-5y^2=5\left(x-1-y\right)\left(x-1+y\right)\)

\(x^2+6x-5x-30=\left(x-5\right)\left(x+6\right)\)

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)

=4x(x²+2)

b)

= (3x-y)²-7²

= (3x-y-7)(3x-y+7)

c)

= (5x²-10x)-(5xy-10y)

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

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

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

a) x³ + 2x²y +  xy² - 9x

= x(x² + 2xy + y² - 9)

= x(x+y)² - 9

= x(x + y - 3) ( x + y + 3).

b) 5x² - 10xy + 5y²

= 5(x² - 2xy + y²)

= 5(x-y)²

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