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17 tháng 8 2018

a) \(5x^2-20x+20y-5y^2\)

\(=5\left(x^2-y^2\right)-20\left(x-y\right)\)

\(=5\left(x-y\right)\left(x+y\right)-20\left(x-y\right)\)

\(=5\left(x-y\right)\left(x+y-4\right)\)

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

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

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

c) \(7x-7y+5x-5y\)

\(=7\left(x-y\right)+5\left(x-y\right)\)

\(=\left(x-y\right)\left(7+5\right)\)

\(=12\left(x-y\right)\)

d) \(16x^2-8x+1\)

\(=\left(4x\right)^2-2.4x+1\)

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

e) \(100x^2-\left(x^2+25\right)^2\)

\(=\left(10x\right)^2-\left(x^2+25\right)^2\)

\(=\left(10x-x^2+25\right)\left(10x+x^2+25\right)\)

\(=\left(10x-x^2+25\right)\left(x+5\right)^2\)

27 tháng 9 2017

a) 5x2y2 + 20x2y4 - 35x5y3 

= \(5x^2y^2\left(1+4y-7x^3y\right)\)

b) 2x ( x + y ) - 7x - 7y

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

c) 5x^2 ( x - 1 ) + 5 ( 1 - x )

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

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

24 tháng 7 2017

a, x2(x-1) - x(x+1)

= (x-1)(x2-x)

b,5x2y3 - 20x3y

= 5x2y.y2 - 5x2y.4x

=5x2y(y2-4x)

c,d,etương tự

11 tháng 10 2020

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

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

c) \(2x^3-x^2-8x+4\)

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

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

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

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

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

e) \(2x^2-5x+2\)

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

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

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

10 tháng 10 2017

Câu a trước đi ạ ^^

a) 7x - 6x- 2

= - 6x2 + 7x - 2

= (- 6x2 + 3x) + (4x - 2)

= 3x (- 2x + 1) + 2 (2x-1)

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

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

30 tháng 10 2016

\(B=7x^2-7xy-5x+5y\)

\(=7x\left(x-y\right)-5\left(x-y\right)\)

\(=\left(x-y\right)\left(7x-5\right)\)

\(E=x^2+7x+12\)

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

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

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

\(F=x^2-9x+18\)

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

\(=x\left(x-3\right)-6\left(x-3\right)\)

\(=\left(x-3\right)\left(x-6\right)\)

\(H=8x^2-2x-1\)

\(=8x^2-4x+2x-1\)

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

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

 

12 tháng 7 2019

a,\(xy+3x-7y-21\)

\(=x\left(y+3\right)-7\left(y+3\right)\)

\(=\left(y+3\right)\left(x-7\right)\)

12 tháng 7 2019

\(b,2xy-15-6x+5y\)

\(=\left(2xy-6x\right)+\left(-15+5y\right)\)

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

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

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

12 tháng 10 2019

a) \(x^4+4x^2-5=x^4+4x^2+4-9=\left(x^2+2\right)^2-3^2\)

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

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

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

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

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

e) \(5x^3-5x^2y-10x^2+10xy=5x^2\left(x-y\right)-10x\left(x-y\right)\)

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

f) \(27x^3-8y^3=\left(3x\right)^3-\left(2y\right)^3=\left(3x-2y\right)\left(9x^2+6xy+4y^2\right)\)

7 tháng 8 2018

b)\(\left(x-5y\right)^2-\left(x+3y\right)^2=\left(x-5y-x-3y\right)\left(x-5y+x+3y\right)\\ =-8y\left(2x-2y\right)=-16\left(x-y\right)\)

c) \(x^2-64=x^2-8^2=\left(x-8\right)\left(x+8\right)\)

d)\(y^{2-100}=y^2:y^{100}=\dfrac{y^2.1}{y^{100}}=\dfrac{1}{y^{98}}\)

e)\(y^2-100=y^2-10^2=\left(y-10\right)\left(y+10\right)\)

16 tháng 8 2018

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