Question

Phân tích thành nhân tử

    x³ - 7x + 6

Answer 1

\(x^3-7x+6\)

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

\(=x^2\left(x-1\right)-2x\left(x-1\right)+3x\left(x-1\right)-6\left(x-1\right)\)

\(=\left(x-1\right)\left(x^2-2x+3x-6\right)\)

\(=\left(x-1\right)\left[\left(x^2-2x\right)+\left(3x-6\right)\right]\)

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

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

Answer 2

Ta có:x³-7x+6

        =x³-x-6x+6

        =x(x²-1)-6(x-1)

        =x(x-1)(x+1)-6(x-1)

        =(x²+x-6)(x-1)

Answer 3

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