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3 tháng 7 2016

chờ xíu đang ghi nha

3 tháng 7 2016

a) \(x^3+3.2x^2y+3.2^2.x.y^2+\left(2y\right)^3=\left(x+2y\right)^3\)

b) áp dụng HDT : \(a^2-b^2=\left(a-b\right)\left(a+b\right)\)

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

c) cũng áp dụng hdt :\(a^2-b^2=\left(a-b\right)\left(a+b\right)\)

\(\Leftrightarrow\left[3\left(x+5\right)\right]^2-\left(x-7\right)^2=\left[3\left(x+5\right)-x+7\right]\left[3\left(x+5\right)+x-7\right]\)\(=\left(3x+15-x+7\right)\left(2x+15+x-7\right)=\left(2x+22\right)\left(3x+8\right)=2\left(x+11\right)\left(3x+8\right)\)

d) áp dụng típ \(a^2-b^2=\left(a-b\right)\left(a+b\right)\)

\(\Leftrightarrow\left[5\left(x-y\right)\right]^2-\left[4\left(x+y\right)\right]^2=\left[5\left(x-y\right)-4\left(x+y\right)\right]\left[5\left(x-y\right)+4\left(x+y\right)\right]\)

\(=\left(5x-5y-4x-4y\right)\left(5x-5y+4x+4y\right)=\left(x-9y\right)\left(9x-y\right)\)

e)Áp dụng típ Hdt như trên

\(\left[7\left(y-4\right)\right]^2-\left[3\left(y+2\right)\right]^2=\left[7\left(y-4\right)-3\left(y+2\right)\right]\left[7\left(y-4\right)+3\left(y+2\right)\right]\)

\(=\left(7y-28-3y-6\right)\left(7y-28+3y+6\right)=\left(4y-34\right)\left(11y-22\right)\)

\(=2\left(2y-17\right).11\left(y-2\right)=22\left(2y-17\right)\left(y-2\right)\)

Bạn 1 cái t i c k nha thật sự rất cảm ơn

6 tháng 7 2016

1. undefined

 

7 tháng 7 2016

\(A=x^2-y^2-x+y\)

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

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

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

\(B=ax-ab+b-x\)

\(=\left(ax-ab\right)-\left(x-b\right)\)

\(=a\left(x-b\right)-\left(x-b\right)\)

\(=\left(a-1\right)\left(x-b\right)\)

\(D=x^2-2xy+y^2-m^2+2mn-n^2\)

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

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

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

\(E=x^2-y^2-2yz-z^2\)

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

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

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

7 tháng 7 2016

 \(=>A=\left(x-y\right)\left(x+y\right)-\left(x-y\right)\\ =>A=\left(x-y\right)\left(x+y-1\right)\) ( dấu phía sau bị lỗi nha )

\(=>B=a\left(x-b\right)-\left(x-b\right)\\ =>B=\left(x-b\right)\left(a-1\right)\)

\(=>C=\left(a+b+c\right)\left(3x^2+36xy+108y^2\right)\)

\(=>C=3\left(a+b+c\right)\left(x^2+12xy+36y^2\right)\\ =>C=3\left(a+b+c\right)\left(x+6y\right)^2\)

\(\Rightarrow D=\left(x-y\right)^2-\left(m^2-2mn+n^2\right)\\ =>D=\left(x-y\right)^2-\left(m-n\right)^2\)

\(=>D=\left(x-y+m-n\right)\left(x-y-m+n\right)\)

\(=>E=x^2-\left(y^2+2yz+z^2\right)\\ =>E=x^2-\left(y+z\right)^2\)

\(=>E=\left(x-y-z\right)\left(x+y+z\right)\)

T I C K ủng hộ nha

CHÚC BẠN HỌC TỐT

10 tháng 8 2016
  • x2.(x3-x2+x-1)
  • x.( x3-3x2-1)+3
  • x.(x2-xy-y2)

    Tìm x:

      x3-16x = 0

     => x.(x2-16) = 0

     => x = 0 hay x2-16 = 0

     => x = 0 hay x2 = 0+16

     => x = 0 hay x2 = 16

     => x = 0 hay x   = 4 hay x = -4

     

8 tháng 7 2015

x2-7x+12

=x2-3x-4x+12

=x(x-3)-4(x-3)

=(x-3)(x-4)

x4-4x2+4x-1

=x4-1-4x2+4x

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

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

=(x-1)[(x+1)(x2+1)-4x]

=(x-1)(x3+x2+x+1-4x)

=(x-1)(x3+x2-3x+1)

6x4-11x2+3

=6x4-2x2-9x2+3

=2x2(3x2-1)-3(3x2-1)

=(3x2-1)(2x2-3)

 

23 tháng 11 2017

+,

= (x-y)^2 - z.(x-y) = (x-y).(x-y-z)

+,

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

+,

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

+,

=a.(x^2-y^2)-7.(x+y) = a.(x+y).(x-y)-7.(x+y) = (ax+ay-7).(x+y)

23 tháng 11 2017

\(x^2-2xy+y^2-xz+yz\)

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

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

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

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

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

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

\(x^4-x^3-x^2+1\)

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

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

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

\(ax^2-ay^2-7x-7y\)

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

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

\(=\left(x-y\right)\left[a\left(x+y\right)-7\right]\)

5 tháng 8 2016

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

\(\Leftrightarrow\left(x^3-4x^2\right)-\left(8x-8\right)\)

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

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

18 tháng 9 2016

\(frac\{3}{4}\)