Question

 phân tích thành nhân tử

a) 5x - 20y                                                                  b) 5x( x - 1 ) - 3x( x - 1 )

c) x( x + y ) - 5x - 5y

Answer 1

a ) \(5x-20y\)

  \(=5.x-5.4y\)

  \(=5.\left(x-4y\right)\)

b ) \(5x\left(x-1\right)-3x\left(x-1\right)\)

   \(=\left(5x-3x\right)\left(x-1\right)\)

   \(=2x\left(x-1\right)\)

c ) \(x\left(x+y\right)-5x-5y\)

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

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

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

Answer 2

a) \(5x-20y=5x-5.4y=5\left(x-4y\right)\)

b) \(5x\left(x-1\right)-3x\left(x-1\right)=\left(x-3x\right)\left(x-1\right)\)

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

 

Answer 3

a/ 5x-20y=5(x-4y)

b/ 5x(x-1) - 3x(x-1) = x(x-1)(5-3)=2x(x-1)

c/ x(x+y)-5x-5y = x(x+y) -5(x+y) = (x-5)(x+y)

Answer 4

a) 5x - 20y       

=5*(x-4y)

b) 5x( x - 1 ) - 3x( x - 1 )

=(x-1)(5x-3x)

=(x-1)2x

c) x( x + y ) - 5x - 5y

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

=(x-5)(x+y)