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23 tháng 12 2016

a, \(x^4+6x^3+7x^2-6x+1\)

\(=x^4-2x^2+1+6x^3+9x^2+6x\)

\(=\left(x^2-1\right)^2+6x\left(x^2-1\right)+9x^2\)

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

b, \(x^4-7x^3+14x^2-7x+1\)

\(=x^4+2x^2+1+7x^3+12x^2-7x\)

\(=\left(x^2+1\right)^2-7x\left(x^2+1\right)+12^2\)

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

c, \(12x^2-11x-36\)

\(=12x^2-27x+16x-36\)

\(=3x\left(4x-9\right)+4\left(4x-9\right)\)

\(=\left(4x-9\right)\left(3x+4\right)\)

15 tháng 11 2016

c​âu c:x^4-2x^3-x^2+x^3-2x^2-x+5x^2-10x-5=x^2(x^2-2x-1)+x(x^2-2x-1)+5(x^2-2x-1)=(x^2-2x-1)(x^2+x+5)

4 tháng 11 2017

\(1.x^4+6x^3+11x^2+6x+1\)

\(=x^4+6x^3+9x^2+2x^2+6x+1\)

\(=x^4+9x^2+1+6x^3+2x^2+6x\)

\(=\left(x^2\right)^2+\left(3x\right)^2+1^2+2.x^2.3x+2.x^2.1+2.3x.1\)

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

\(2,6x^4+5x^3-38x^2+5x+6\)

\(=6x^4+6x^3+2x^3-3x^3-36x^2+2x^2-3x^2-x^2-12x+18x-x+6\)

\(=\left(6x^4+2x^3\right)+\left(6x^3+2x^2\right)-\left(3x^3+x^2\right)-\left(36x^2+12x\right)+\left(18x+6\right)-\left(3x^2+x\right)\)

\(=2x^3\left(3x+1\right)+2x^2\left(3x+1\right)-x^2\left(3x+1\right)-12x\left(3x+1\right)+6\left(3x+1\right)-x\left(3x+1\right)\)

\(=\left(3x+1\right)\left(2x^3+2x^2-x^2-12x+6-x\right)\)

\(=\left(3x+1\right)\left[\left(2x^3-x^2\right)+\left(2x^2-x\right)-\left(12x-6\right)\right]\)

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

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

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

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

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

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

4 tháng 11 2017

1. \(x^4+6x^3+11x^2+6x+1\)

\(=\left(x^2\right)^2+2.x^2.3x+\left(3x\right)^2+2x^2+6x+1\)

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

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

3. \(x^4-7x^3+14x^2-7x+1\)

\(=x^2\left(x^2-7x+14-\dfrac{7}{x}+\dfrac{1}{x^2}\right)\)

\(=x^2\left[\left(x^2+\dfrac{1}{x^2}\right)-\left(7x+\dfrac{7}{x}\right)+14\right]\)

\(=x^2\left[\left(x+\dfrac{1}{x}\right)^2-7\left(x+\dfrac{1}{x}\right)+12\right]\)

\(=x^2\left[\left(x+\dfrac{1}{x}\right)^2-2\left(x+\dfrac{1}{x}\right).\dfrac{7}{2}+\dfrac{49}{4}-\dfrac{1}{4}\right]\)

\(=x^2\left[\left(x+\dfrac{1}{x}-\dfrac{7}{2}\right)^2-\dfrac{1}{4}\right]\)

\(=\left(x^2+1-\dfrac{7}{2}x\right)^2-\left(\dfrac{1}{2}x\right)^2\)

\(=\left(x^2-3x+1\right)\left(x^2-4x+1\right)\)

Có thể phân tích thành HĐT tiếp hoặc không.

13 tháng 11 2016

a) nhận xét hệ số : 1 + 4 - 29 + 24 = 0

=> x3 + 4x2 - 29x + 24 = x2(x-1) + 5x(x-1) - 24(x-1)

= (x-1)(x2+5x-24) = (x-1)(x-3)(x+8)

b) ...

13 tháng 11 2016

a) \(x^3+4x^2-29x+24\)=\(\left(x+8\right)\left(x^2-4x+3\right)\)=\(\left(x+8\right)\left(x^2-x-3x+3\right)\)=\(\left(x+8\right)\left(x-1\right)\left(x-3\right)\)

b) \(x^4+6x^3+7x^2-6x+1\)=\(x^4+3x^3-x^2+3x^3+9x^2-3x-x^2-3x+1\)=\(x^2\left(x^2+3x-1\right)+3x\left(x^2+3x-1\right)-\left(x^2+3x-1\right)\)=\(\left(x^2+3x-1\right)\left(x^2+3x-1\right)\)=\(\left(x^2+3x-1\right)^2\)

28 tháng 9 2017

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

\(=x^4-2x^3+6x^2-8x+8=\left(x^4-2x^3+2x^2\right)+\left(4x^2-8x+8\right)\)

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

b)\(x^4+6x^3+7x^2-6x+1=\left(x^2\right)^2+\left(3x\right)^2+\left(-1\right)^2+2.x^2.3x\)+2.3x.(-1)+2.x2.(-1)

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

5 tháng 11 2018

a) \(x^{12}-3x^6+1\)

\(=\left(x^6\right)^2-2\cdot x^6\cdot1+1^2-x^6\)

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

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

5 tháng 11 2018

b) \(x^4+6x^3+7x^2-6x+1\)

\(=x^4+\left(6x^3-2x^2\right)+\left(9x^2-6x+1\right)\)

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

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