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21 tháng 4 2020

1.

7x(2x-1)=14x2-7x

2

a. x2+2x=x(x+2)

b.x2-xy+3x-3y

=x(x-y)+3(x-y)

=(x+3)(x-y)

Câu 2:

 1. 2x/2x-5 -  5/2x-5

=2x-5/2x-5

=1

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

26 tháng 7 2017

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

kl: ...

b) \(=\left(x+2\right)\left(x^2-8x-15\right)=\left(x+2\right)\left(x-5\right)\left(x-3\right)\)

kl:....

26 tháng 7 2017

a, \(x^3-9x^2+6x+16\)

\(=x^3-8x^2-x^2+8x-2x+16\)

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

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

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

\(=\left(x-8\right)\left[x\left(x-2\right)+\left(x-2\right)\right]\)

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

b, \(x^3-6x^2-x+30\)

\(=x^3-5x^2-x^2+5x-6x+30\)

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

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

\(=\left(x-5\right)\left(x^2-3x+2x-6\right)\)

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

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

Chúc bạn học tốt!!!

\(a)\)

\(4x^2-y^2+2x+y\)

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

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

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

\(b)\)

\(x^3+2x^2-6x-27\)

\(=x^3+5x^2+9x-3x^2-15x-27\)

\(=x\left(x^2+5x+9\right)-3\left(x^2+5x-9\right)\)

\(=\left(x-3\right)\left(x^2+5-9\right)\)

\(c)\)

\(12x^3+4x^2-27x-9\)

\(=\left(12x^3+4x^2\right)-\left(27x+9\right)\)

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

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

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

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

\(d)\)

\(16x^2+4x-y^2+y^2\)

\(=16x^2+4x\)

\(4x\left(4x+1\right)\)

\(x^2+6x-y^2+9\)

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

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

\(=\left(x+3-y\right)\left(x+3+y\right)\)

28 tháng 8 2016

mk ghi thiếu nưAx là 

27x3+\(\frac{1}{8}\)

(x+y)3-(x-y)3

2 tháng 8 2017

a)

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

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

b)

\(1-2x+2yz+x^2-y^2-z^2=\left(x^2-2x+1\right)-\left(y^2-2yz+z^2\right)\) (đổi dấu)

\(=\left(x-1\right)^2-\left(y-z\right)^2\)

c)

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

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

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

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

2 tháng 8 2017

(2x-3y)(2x+3y) chớ x + 3 k ik

11 tháng 10 2017

b)3x^2-18x+27=3x^2-9x-9x+27=3x*(x-3)-9*(x-3)=(x-3)*(3x-9)=(x-3)*3*(x-3)=3*(x-3)^2

c)x^3-4x^2-12x+27=(x+3)*(x^2-3x+9-4)=(x+3)*(x^2-3x+5)

d)27x^3-1/27=(3x-1/3)*(9x^2-x+1/9)   (hang dt)

con a) voi e) mk chiu

29 tháng 1 2020

a) \(6x^2-x-1\)

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

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

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

29 tháng 1 2020

b) \(6x^2-6x-3\)

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

19 tháng 12 2016

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