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20 tháng 6 2019

\(x^3-2x^2-5x+6\)

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

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

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

20 tháng 6 2019

1. \(x^3-2x-5x+6\)

\(\Leftrightarrow x^2\left(x-3\right)+x\left(x-3\right)-2\left(x-3\right)\)

\(\Leftrightarrow\left(x-3\right)\left(x^2+x-2\right)\)

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

2. \(x^3-7x^2+15x-9\)

\(\Leftrightarrow\left(x^3-x^2\right)-\left(6x^2-6x\right)+\left(9x-9\right)\)

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

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

\(\Leftrightarrow\left(x-1\right)\left(x\left(x-3\right)-3\left(x-3\right)\right)\)

\(\Leftrightarrow\left(x-1\right)\left(x-3\right)^2\)

29 tháng 12 2016

\(3x^2-5x+2=3x^2-3x-2x+2=3x\left(x-1\right)-2\left(x-1\right)=\left(3x-2\right)\left(x-1\right)\)

29 tháng 12 2016

b.)x^4+5x^3+15x-9 

=x^4-9+5x^3+15x

=(x^2-3)(x^2+3)+5x(x^2+3)

=(x^2+3)(x^2-3+5x)

4 tháng 8 2017

Mình sửa: Bài 1
2)x2+3x-15

20 tháng 5 2018

a) x2 + 6x + 9 = x2 + 2 . x . 3 + 32 = (x + 3)2

b) 10x – 25 – x2 = -(-10x + 25 +x2) = -(25 – 10x + x2)

                         = -(52 – 2 . 5 . x – x2) = -(5 – x)2

c) 8x3 - 1/8 = (2x)3 – (1/2)3 = (2x - 1/2)[(2x)2 + 2x . 12 + (1/2)2]

                    = (2x - 1/2)(4x2 + x + 1/4) 

d)1/25x2 – 64y2 = (1/5x)2(1/5x)2- (8y)2 = (1/5x + 8y)(1/5x - 8y)

4 tháng 8 2015

x^4+ 2x^2 + 5x^3 + 10x- 2x^2  - 4

= x^2. [x^2+ 2 ] +5.x[x^2+2] - 2.[x^2+2]

= [x^2+5x-2] . [x^2+2]

26 tháng 9 2017

làm nhanh cho tui đi nhé

12 tháng 9 2018

a) \(x^3-x^2-4\)

\(=x^3-2x^2+x^2-2x+2x-4\)

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

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

b) \(x^3+x^2-10x+8\)

\(=x^3+4x^2-3x^2-12x+2x+8\)

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

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

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

c) \(x^3-13x-12\)

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

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

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

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

f) \(x^3+5x^2+8x+4\)

\(=x^3+x^2+4x^2+4x+4x+4\)

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

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

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

12 tháng 9 2018

      \(x^3-x^2-4\)

\(=x^3-2x^2+x^2-2x+2x-4\)

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

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

b,   \(x^3+x^2-10x+8\)

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

\(=x^2\left(x-1\right)+2x\left(x-1\right)-8\left(x-1\right)\)

\(=\left(x-1\right)\left(x^2+2x-8\right)\)

\(=\left(x-1\right).\left[x^2+4x-2x-8\right]\)

\(=\left(x-1\right).\left[x\left(x+4\right)-2\left(x+4\right)\right]\)

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

c,   \(x^3-13x-12\)

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

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

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

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

d,   \(x^3+5x^2+8x+4\)

\(=x^3+x^2+4x^2+4x+4x+4\)

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

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

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

Chúc bạn học tốt.

23 tháng 9 2016

a) Hình như phân tích không được

b)  \(2x^4+5x^3+13x^2+25x+15\)

\(=x^3+1+2x^4+2x^3+13x^2+13x+12x+12+2+2x^3\)

\(=\left(x^3+1\right)+\left(2x^4+2x^3\right)+\left(13x^2+13x\right)+\left(12x+12\right)+2\left(1+x^3\right)\)

\(=\left(x+1\right)\left(x^2-x+1\right)+2x^3\left(x+1\right)+13x\left(x+1\right)+12\left(x+1\right)+2\left(x+1\right)\left(x^2-x+1\right)\)

\(=\left(x+1\right)\left(x^2-x+1+2x^3+13x+12+2x^2-2x+2\right)\)

\(=\left(x+1\right)\left(3x^2+10x+15+2x^3\right)\)

\(=\left(x+1\right)\left[x^2\left(2x+3\right)+5\left(2x+3\right)\right]\)

\(=\left(x+1\right)\left(x^2+5\right)\left(2x+3\right)\)