Question

đặt nhân tử chung 

a  x^2 -x^3 -9y +9x

b   x^3 +6x^2 +9x

c  x^2 -xy +x - y

d  x^2 +x -xy -y

Answer 1

b: =x(x^2+6x+9)

=x(x+3)^2

c: =(x^2-xy)+(x-y)

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

=(x-y)(x+1)

d: =(x^2+x)-(xy+y)

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

=(x+1)(x-y)

Answer 2

b) \(x^3+6x^2+9x\)

\(=x\cdot\left(x^2+6x+9\right)\)

\(=x\cdot\left(x^2+2\cdot3\cdot x+3^2\right)\)

\(=x\cdot\left(x+3\right)^2\)

c) \(x^2-xy+x-y\)

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

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

\(=\left(x-y\right)\left(x+1\right)\)

d) \(x^2+x-xy-y\)

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

\(=x\left(x+1\right)-y\left(x+1\right)\)

\(=\left(x-y\right)\left(x+1\right)\)