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19 tháng 8 2020

a, -x - y2 + x2 - y = (x2 - y2) - (x + y)

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

= (x + y)(x - y - 1)

b, x( x + y ) - 5x - 5y = x(x + y) - 5(x + y)

= (x - 5)(x + y)
c, x2 - 5x + 5y - y2 = (x - y)(x + y) - 5(x - y)

= (x - y)(x + y - 5)
d, 5x3 - 5x2y - 10x2 + 10xy = 5x2(x - y) - 10x(x - y)

= 5x(x - y)(x - 2)
e, 27x3 - 8y3 = (3x - 2y)(9x2 + 6xy + 4y2)
f, x2 - y2 - x - y = (x - y)(x + y) - (x + y)

= (x + y)(x - y - 1)
g, x2 - y2 - 2xy + y2 = (x2 - 2xy + y2) - y2

= (x - y)2 - y2

= (x - y - y)(x - y + y) = x(x - 2y)
h, x2 - y2 + 4 - 4x = (x2 - 4x + 4) - y2

= (x - 2)2 - y2

= (x - y - 2)(x + y - 2)
i, x3 + 3x2 + 3x + 1 - 27z3 = (x + 1)3 - 27z3

= (x+1-3z)(x2+2x+1+3xz+3z+9z2)
k, 4x2 + 4x - 9y2 + 1 = (2x + 1)2 - 9y2

= (2x - 3y + 1)(2x + 3y + 1)
m, x2 - 3x + xy - 3y = x(x - 3) + y(x - 3)

= (x - 3)(x + y)

19 tháng 8 2020

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

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

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

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

b) \(x\left(x+y\right)-5x-5y\)

\(=x\left(x+y\right)-5\left(x+y\right)\)

\(=\left(x+y\right)\left(x-5\right)\)

c) \(x^2-5x+5y-y^2\)

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

\(=\left(x-y\right)\left(x+y\right)-5\left(x-y\right)\)

\(=\left(x-y\right)\left(x+y-5\right)\)

d) \(5x^3-5x^2y-10x^2+10xy\)

\(=5x\left(x^2-xy-2x+2y\right)\)

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

\(=5x\left(x-y\right)\left(x-2\right)\)

e) \(27x^3-8y^3\)

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

\(=\left(3x-2y\right)\left[\left(3x\right)^2+3x2y+\left(2y\right)^2\right]\)

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

f) \(x^2-y^2-x-y\)

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

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

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

g) \(x^2-y^2-2xy+y^2\)

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

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

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

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

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

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

\(=\left(x^2-2.2x+2^2\right)-y^2\)

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

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

i) \(x^6-y^6\)

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

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

\(=\left[\left(x-y\right)\left(x^2+xy+y^2\right)\right]\left[\left(x+y\right)\left(x^2-xy+y^2\right)\right]\)

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

4 tháng 11 2019

a) \(x^3-3x^2+1-3x\)

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

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

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

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

\(=\left(x+1\right)\left(x^2-4x+4-5\right)\)

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

\(=\left(x+1\right)\left(x-2-\sqrt{5}\right)\left(x-2+\sqrt{5}\right)\)

b) \(x^2-6xy-25z^2+9y^2\)

\(=\left(x^2-6xy+9y^2\right)-25z^2\)

\(=\left(x-3y\right)^2-25z^2\)

\(=\left(x-3y-5z\right)\left(x-3y+5z\right)\)

c) \(x^2-y^2-x-y\)

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

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

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

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

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

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

e) \(a^3-ay-a^2x+xy\)

\(=a\left(a^2-y\right)-x\left(a^2-y\right)\)

\(=\left(a^2-y\right)\left(a-x\right)\)

23 tháng 12 2019

a) \(A=5x\left(4x^2-2x+1\right)-2x\left(10x^2-5x-2\right)\)

\(A=20x^3-10x^2+5x-20x^3+10x^2+4x\)

\(A=9x\)

Thay x = 15 vào, ta có: 

\(A=9.15=135\)

b) \(B=5x\left(x-4y\right)-4y\left(y-5x\right)\)

\(B=5x^2-20xy-4y^2+20xy\)

\(B=5x^2-4y\)

Thay \(x=-\frac{1}{5};y=-\frac{1}{2}\) vào, ta có: 

\(B=5.\left(-\frac{1}{5}\right)^2-4.\left(-\frac{1}{2}\right)=\frac{11}{5}\)

c) \(C=6xy\left(xy-y^2\right)-8x^2\left(x-y^2\right)-5y^2\left(x^2-xy\right)\)

\(C=6x^2y^2-6xy^3-8x^3+8x^2y^2-5x^2y^2+5xy^3\)

\(C=9x^2y^2-xy^3-8x^3\)

Thay \(x=\frac{1}{2};y=2\) vào, ta có:

\(C=9.\left(\frac{1}{2}\right)^2.2^2-\frac{1}{2}.2^3-8.\left(\frac{1}{2}\right)^3=4\)

d) \(D=\left(3x+5\right)\left(2x-1\right)+\left(4x-1\right)\left(3x+2\right)\)

\(D=6x^2-3x+10x-5+12x^2+8x-3x-2\)

\(D=18x^2+12x-7\)

Ta có: \(\left|2\right|=\orbr{\begin{cases}x=-2\\x=2\end{cases}}\)

+) Với x = -2

\(D=18.\left(-2\right)^2+12.\left(-2\right)-7=41\)

+) Với x = 2

\(D=18.2^2+12.2-7=89\)

29 tháng 7 2017

a)      \(x^3+2x^2-3x-6\)

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

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

b)     \(5x^2\left(x-1\right)-10xy\left(x-1\right)-5y^2\left(1-x\right)\)

\(=5x^2\left(x-1\right)-10xy\left(x-1\right)+5y^2\left(x-1\right)\)

\(=\left(5x^2-10xy+5y^2\right)\left(x-1\right)\)

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

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

c)   \(x^2-6xy+9y^2-9\)

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

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

\(\left(x-6\right)x\)

cái thứ 2 và 5 ko hiểu j nên ko làm

29 tháng 7 2017

mk làm lun nha 

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

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

2.= 2ac(a-b)- d(a-b)

= (2ac-d)(a-b)

3,= (x-1)(5x^2-10xy+5x^2)

= 5(x-1)(x^2-2xy+y^2)

= 5(x-1)(x-y)^2

4, = (x^2-6xy+9y^2)-9

= (x-3y)^2-3^2

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

3 tháng 8 2018

13 

25

234

81 

316

 nhớ cho mình 1 k

19 tháng 6 2015

a) x^2+2xy+y^2-16

=(x+y)2-16

=(x+y-4)(x+y+4)

b) 3x^2+5x-3xy-5y

=(3x2-3xy)+(5x-5y)

=3x(x-y)+5(x-y)

=(x-y)(3x+5)

c) 4x^2-6x^3y-2x^2+8x

ko bik hoặc sai đề

d) x^2-4-2xy+y^2

=(x-y)2-4

=(x-y+2)(x-y-2)

e) x^3-4x^2-12x+27

=sai đề

g) 3x^2-18x+27

=3(x2-6x+9)

=3(x-3)2

h) x^2-y^2-z^2-2yz

=x2-(y2+z2+2yx)

=x2-(y+z)2

=(x-y-z)(x+y+z)

k) 4x^2(x-6)+9y^2(6-x)

=4x2(x-6)-9y2(x-6)

=(x-6)(4x2-9y2)

=(x-6)(2x-3y)(2x+3y)

l)6xy+5x-5y-3x^2-3y^2

=(5x-5y)+(-3x2+6xy-3y2)

=5(x-y)-3(x2-2xy+y2)

=5(x-y)-3(x-y)2

=(x-y)(5-3(x-y))

=(x-y)(5-3x+3y)

20 tháng 10 2023

a) Xem lại đề

b) x³ - 4x²y + 4xy² - 9x

= x(x² - 4xy + 4y² - 9)

= x[(x² - 4xy + 4y² - 3²]

= x[(x - 2y)² - 3²]

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

c) x³ - y³ + x - y

= (x³ - y³) + (x - y)

= (x - y)(x² + xy + y²) + (x - y)

= (x - y)(x² + xy + y² + 1)

d) 4x² - 4xy + 2x - y + y²

= (4x² - 4xy + y²) + (2x - y)

= (2x - y)² + (2x - y)

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

e) 9x² - 3x + 2y - 4y²

= (9x² - 4y²) - (3x - 2y)

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

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

f) 3x² - 6xy + 3y² - 5x + 5y

= (3x² - 6xy + 3y²) - (5x - 5y)

= 3(x² - 2xy + y²) - 5(x - y)

= 3(x - y)² - 5(x - y)

= (x - y)[(3(x - y) - 5]

= (x - y)(3x - 3y - 5)