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4 tháng 2 2018

\(x^2+2xy+7x+7y+y^2+10\)

\(=\left(x^2+2xy+y^2\right)+\left(7x+7y\right)+\frac{49}{4}-\frac{9}{4}\)

\(=\left(x+y\right)^2+7\left(x+y\right)+\frac{49}{4}-\frac{9}{4}\)

\(=\left(x+y+\frac{7}{2}\right)^2-\frac{9}{4}\)

\(=\left(x+y+\frac{7}{2}-\frac{3}{2}\right)\left(x+y+\frac{7}{2}+\frac{3}{2}\right)\)

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

4 tháng 2 2018

b)Ta có: x2y+xy2+x+y=2010

<=>xy.x+xy.y+x+y=2010

<=>11x+11y+x+y=2010

<=>12(x+y)=2010

<=>x+y=167,5

=>(x+y)2=28056,25

<=>x2+y2+2xy=28056,25

<=>x2+y2=28034,25

a: \(=\left(x^2+2xy+y^2\right)+7\left(x+y\right)+10\)

\(=\left(x+y\right)^2+7\left(x+y\right)+10\)

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

b: \(x^2y+xy^2+x+y=2010\)

\(\Leftrightarrow xy\left(x+y\right)+x+y=2010\)

\(\Leftrightarrow\left(x+y\right)\left(xy+1\right)=2010\)

\(\Leftrightarrow x+y=167.5\)

\(x^2+y^2=\left(x+y\right)^2-2xy=167.5^2-22=28034.25\)

2 tháng 9 2021

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

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

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

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

26 tháng 11 2023

x²y + xy² - x - y

= (x²y + xy²) - (x + y)

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

= (x + y)(xy - 1)

3 tháng 10 2017

Ta có: ( xy+1)^2 - (x+y)^2

= x^2.y^2 + 2xy + 1^2 - x^2 -2xy - y^2

= x^2. y^2 - x^2 - y^2 +1

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

= (x^2 - 1)(y^2-1) 

17 tháng 11 2021

\(a,Sửa:x^2-xy-13x+13y=x\left(x-y\right)-13\left(x-y\right)=\left(x-13\right)\left(x-y\right)\\ b,=\left(x+y\right)^2-\left(2z\right)^2=\left(x+y-2z\right)\left(x+y+2z\right)\\ c,=\left(x^2-2x\right)-\left(3x-6\right)=x\left(x-2\right)-3\left(x-2\right)=\left(x-2\right)\left(x-3\right)\)

29 tháng 12 2017

B1 :

a, B = (x+1)^2+(y-2)^2 = (99+1)^2+(102-2)^2 =  100^2+100^2 = 20000

b, = (2x^2+16x+32)-2y^2

   = 2.(x+4)^2-2y^2

   = 2.[(x+4)^2-y^2] = 2.(x+4-y).(x+4+y)

c, <=> (x^2-3x)+(2x-6) = 0

<=> (x-3).(x+2) = 0

<=> x-3=0 hoặc x+2=0

<=> x=3 hoặc x=-2

B2 :

P = (3-x).(x+3)/x.(x-3) = -(x+3)/x = -x-3/x

k mk nha

29 tháng 12 2017

Bai 1

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

     Voi x=99,y=102

=>B= 1002+1002

       =20000

b)\(2x^2-2y^2+16x+32\)

=\(2\left[\left(x^2+8x+16\right)-y^2\right]\)

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

=2(x-y+4)(x+y+4)

c)\(x^2-3x+2x-6=0\)

=>x(x-3)+2(x-3)=0

=>(x-3)(x+2)=0

=>x=-2;3

Bai 2

\(P=\frac{9-x^2}{x^2-3x}\)

    =\(-\frac{x^2-9}{x\left(x-3\right)}\)

   =\(-\frac{\left(x-3\right)\left(x+3\right)}{x\left(x-3\right)}\)

=\(\frac{-x-3}{x}\)

2: \(8xy-24xy+16x\)

\(=8x\cdot y-8x\cdot3y+8x\cdot2\)

\(=8x\left(y-3y+2\right)=8x\left(-2y+2\right)\)

\(=-16y\left(y-1\right)\)

3: \(xy-x=x\cdot y-x\cdot1=x\left(y-1\right)\)

11: \(2mx-4m2xy+6mx\)

\(=2mx-2my\cdot4y+2mx\cdot3\)

\(=2mx\left(1-4y+3\right)\)

\(=2mx\left(4-4y\right)=8mx\left(1-y\right)\)

12: \(7x^2y^5-14x^3y^4-21y^3\)

\(=7y^3\cdot x^2y^2-7y^3\cdot2x^3y-7y^3\cdot3\)

\(=7y^3\left(x^2y^2-2x^3y-3\right)\)

13: \(2\left(x-y\right)-a\left(x-y\right)\)

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

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