Question

pt các đa thức thành nhân tử

a,x(x-7)+(7-x)^2 ,

b,3x(x-9)^2-(9-x)^3

Answer 1

a) = x.(x-7) + (x-7)^2

    = (x-7).(x + x - 7)

    = (x-7).(2x-7)

b) = 3x.(9-x)^2 - (9-x)^3

    = (9-x)^2.(3x - 9 + x)

    = (9-x)^2.(4x-9)

Answer 2

a: \(x\left(x-7\right)+\left(7-x\right)^2\)

\(=x\left(x-7\right)+\left(x-7\right)^2\)

\(=\left(x-7\right)\left(x+x-7\right)\)

\(=\left(x-7\right)\left(2x-7\right)\)

b: \(3x\left(x-9\right)^2-\left(9-x\right)^3\)

\(=3x\left(x-9\right)^2+\left(x-9\right)^3\)

\(=\left(x-9\right)^2\left[3x+x-9\right]\)

\(=\left(x-9\right)^2\cdot\left(4x-9\right)\)