Question

phân tích đa thức thành nhân tử

x³ - 7x +6

Answer 1

x³-7x+6=x³-x-6x+6=x(x-1)(x+1)-6(x-1)=(x-1)(x²+x-6)=(x-1)(x-2)(x+3)

Answer 2

\(x^3-7x+6=x^3+3x^2-3x^2-9x+2x+6\)

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

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

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

\(=\left(x+3\right).\left[x.\left(x-1\right)-2.\left(x-1\right)\right]\)

\(=\left(x+3\right).\left(x-1\right).\left(x-2\right)\)