Question

Phân tích đa thức thành nhân tử: x³ - 7x - 6

Answer 1

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

=(x² - 3x + 2x - 6)(x+1)

=[x(x+2)-3(x+2)](x+1)

=(x-3)(x+2)(x+1)

Answer 2

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

Answer 3

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

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

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

\(=x\left(x+1\right)\left(x-1\right)-6\left(x+1\right)\)

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

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

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

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

Answer 4

           Bài làm :

Ta có :

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

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

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

\(=x\left(x+1\right)\left(x-1\right)-6\left(x+1\right)\)

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

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

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

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