Question

Phân tích đa thức thành nhân tử

a) 3xy - 6y

b) x(x+y)+2x+2y

c) y^2 -81

Answer 1

a)\(3xy-6y=3y\left(x-2\right)\)

b)\(x\left(x+y\right)+2x+2y=x\left(x+y\right)+\left(2x+2y\right)=x\left(x+y\right)+2\left(x+y\right)=\left(x+y\right)\left(x+2\right)\)

c)\(y^2-81=y^2-9^2=\left(y-9\right)\left(y+9\right)\)

Answer 2

a)`3xy-6y`

`=3y(x-2)`

b)`x(x+y)+2x+2y`

`=x(x+y)+2(x+y)`

`=(x+y)(x+2)`

c)`y^2 -81`

`=y^2-9^2`

`=(y-9)(y+9)`