Question

[NOOB]

Phân tích đa thức thành nhân tử
a) \(3\left(x-y\right)-5x\left(y-x\right)\)
b) \(x^3+2x^2y+xy^2-9x\)

c)\(14x^2y-21xy^2+28x^2y^2\)

Answer 1

[l҉o҉n҉g҉ d҉z҉]

a) 3( x - y ) - 5x( y - x )

= 3( x - y ) - 5x[ -( x - y ) ]

= 3( x - y ) + 5x( x - y )

= ( 3 + 5x )( x - y )

b) x³ + 2x²y + xy² - 9x

= x( x² + 2xy + y² - 9 )

= x[ ( x + y )² - 3² ]

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

c) 14x²y - 21xy² + 28x²y²

= 7xy( 2x - 3y + 4xy )

Answer 2

[Fudo]

                                              Bài giải

\(a,\text{ }3\left(x-y\right)-5x\left(y-x\right)\)

\(=3\left(x-y\right)+5x\left(x-y\right)\)

\(=\left(x-y\right)\left(3+5x\right)\)

\(b,\text{ }x^3+2x^2y+xy^2-9x\)

\(=x\left(x^2+2xy+y^2-9\right)\)

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

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

\(c,\text{ }14x^2y-21xy^2+28x^2y\)

\(=7xy\left(2x-3y+4x\right)\)

\(=7xy\left(6x-3y\right)\)