\(b,=x^4-2x^3-x^3+2x^2+3x^2-6x-3x+6\\ =\left(x-2\right)\left(x^3-x^2+3x-3\right)\\ =\left(x-2\right)\left(x-1\right)\left(x^2+3\right)\\ c,=x^4-2x^3+4x^3-8x^2+4x^2-8x+3x-6\\ =\left(x-2\right)\left(x^3+4x^2+4x+3\right)\\ =\left(x-2\right)\left(x^3+3x^2+x^2+3x+x+3\right)\\ =\left(x-2\right)\left(x+3\right)\left(x^2+x+1\right)\)

 x⁴+2.x³-13.x²-14x+24

=x³.(x+2)-13x²+12x-26x+24

=x³.(x+2)-x.(13x-12)-2.(13x-12)

=x³.(x+2)-(13x-12)(x+2)

=(x+2)(x³-13x+12)

=(x+2)(x³-x-12x+12)

=(x+2)[x.(x²-1)-12.(x-1)]

=(x+2)[x.(x-1)(x+1)-12.(x-1)]

=(x+2)(x-1)[x.(x+1)-12]

=(x+2)(x-1)(x²+x-12)

=(x+2)(x-1)(x²-3x+4x-12)

=(x+2)(x-1)[x.(x-3)+4.(x-3)]

=(x+2)(x-1)(x-3)(x+4)

\(x^3-x^2-14x+24\)

\(=x^3-2x^2+x^2-2x-12x+24\)

\(=x^2\left(x-2\right)+x\left(x-2\right)-12\left(x-2\right)\)

\(=\left(x-2\right)\left(x^2+x-12\right)\)

\(=\left(x-2\right)\left(x^2+4x-3x-12\right)\)

\(=\left(x-2\right)\left[x\left(x+4\right)-3\left(x+4\right)\right]\)

\(=\left(x-2\right)\left(x+4\right)\left(x-3\right)\)

Ta có:\(x^3-x^2-14x+24=\left(x^3-2x^2\right)+\left(x^2-2x\right)-\left(12x-24\right)\)

                                                    \(=x^2\left(x-2\right)+x\left(x-2\right)-12\left(x-2\right)\)

                                                    \(=\left(x-2\right)\left(x^2+x-12\right)\)

                                                    \(=\left(x-2\right)\left(x^2-3x+4x-12\right)\)

                                                    \(=\left(x-2\right)\left[x\left(x-3\right)+4\left(x-3\right)\right]\)

                                                    \(=\left(x-2\right)\left(x+4\right)\left(x-3\right)\)

Ta có:

\(x^3-x^2-14x+24\) \(=x^3+4x^2-5x^2-20x+6x+24\)

                                                    \(=x^2\left(x+4\right)-5x\left(x+4\right)+6\left(x+4\right)\)

                                                    \(=\left(x+4\right)\left(x^2-5x+6\right)\)

                                                    \(=\left(x+4\right)\left(x^2-3x-2x+6\right)\)

                                                    \(=\left(x+4\right)[x\left(x-3\right)-2\left(x-3\right)]\)

                                                    \(=\left(x+4\right)\left(x-2\right)\left(x-3\right).\)

Vậy \(x^3-x^2-14x+24=\left(x+4\right)\left(x-2\right)\left(x-3\right).\)

a) \(x^3-7x-6=x^3-x^2+x^2-7x-6=x^2\left(x-1\right)+x^2-x-6x+6\)

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

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

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

b)\(x^3-x^2-14x+24=x^3-3x^2+2x^2-6x-8x+24\)

\(=x^2\left(x-3\right)+2x\left(x-3\right)-8\left(x-3\right)\)

\(=\left(x-3\right)\left(x^2+2x-8\right)=\left(x-3\right)\left(x^2-2x+4x-8\right)\)

\(=\left(x-3\right)\left(x\left(x-2\right)+4\left(x-2\right)\right)=\left(x-3\right)\left(x-2\right)\left(x+4\right)\)

  CÓ CHỖ NÀO KO HIỂU GỬI THƯ HỎI MIK , MIK NÓI CHO !!~  HOK TỐT ~

Lời giải:
a. $x^3-4x^2+x+6=(x^3-2x^2)-(2x^2-4x)-(3x-6)$

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

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

-------------------

b.

$x^3+7x^2+14x+8=(x^3+x^2)+(6x^2+6x)+(8x+8)$

$=x^2(x+1)+6x(x+1)+8(x+1)=(x+1)(x^2+6x+8)$

$=(x+1)[(x^2+2x)+(4x+8)]=(x+1)[x(x+2)+4(x+2)]$

$=(x+1)(x+2)(x+4)$

 Câu a bạn xem lại đề bài nhé. Đa thức đề cho thậm chí còn không có nghiệm hữu tỉ luôn cơ.

 b) Lập sơ đồ Horner:

\(\Rightarrow x^3+7x^2+14x+8=\left(x+1\right)\left(x^2+6x+8\right)\)

 Ta thấy đa thức \(g\left(x\right)=x^2+6x+8\), dự đoán được 1 nghiệm \(x=-2\). Ta lại lập sơ đồ Horner:

\(\Rightarrow g\left(x\right)=\left(x+2\right)\left(x+4\right)\)

Vậy đa thức đã cho có thể được phân tích thành \(\left(x+1\right)\left(x+2\right)\left(x+4\right)\)

Bài 1:

a: \(5x^3+10xy=5x\left(x^2+2y\right)\)

b: \(x^2+14x+49-y^2\)

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

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