\(x^2-8x-9\) 

d) \(x^...">

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27 tháng 10 2018

c) x2 - 8x - 9

= x2 + x - 9x - 9

= x.(x+1) - 9.(x+1)

= (x+1).(x-9)

d) x2 + 14x + 48

= x2 + 8x + 6x + 48

= x.(x+8) + 6.(x+8)

= (x+8).(x+6)

27 tháng 10 2018

c/ \(x^2-8x-9=\left(x^2+x\right)-\left(9x+9\right)=x\left(x+1\right)-9\left(x+1\right)=\left(x+1\right)\left(x-9\right)\)

d/ \(x^2+14x+48=x^2+6x+8x+48=x\left(x+6\right)+8\left(x+6\right)=\left(x+6\right)\left(x+8\right)\)

3 tháng 8 2018

c) x2 - x + 9x - 9

=(x2-x) +  (9x-9)

= x(x-1) + 9(x-1)

= (x-1)(x+9)

3 tháng 8 2018

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

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

d) \(x^2+14x+48=\left(x+7\right)^2-1=\left(x+7+1\right)\left(x+7-1\right)=\left(x+8\right)\left(x+6\right)\)

26 tháng 9 2018

      \(x^3-x^2-14x+24\)

\(=x^3-2x^2+x^2-2x-12x+24\)

\(=x^2\left(x-2\right)+x\left(x-2\right)-12\left(x-2\right)\)

\(=\left(x-2\right)\left(x^2+x-12\right)\)

\(=\left(x-2\right).\left[x^2+4x-3x-12\right]\)

\(=\left(x-2\right).\left[x\left(x+4\right)-3\left(x+4\right)\right]\)

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

      \(x^4+x^3+2x-4\)

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

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

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

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

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

      \(8x^4-2x^3-3x^2-2x-1\)

\(=8x^4-8x^3+6x^3-6x^2+3x^2-3x+x-1\)

\(=8x^3\left(x-1\right)+6x^2\left(x-1\right)+3x\left(x-1\right)+x-1\)

\(=\left(x-1\right)\left(8x^3+6x^2+3x+1\right)\)

\(=\left(x-1\right)\left[\left(8x^3+1\right)+\left(6x^2+3x\right)\right]\)

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

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

      \(3x^2-7x+2\)

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

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

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

Chúc bạn học tốt.

5 tháng 7 2016

a) \(x^2+4x+3=\left(x^2+4x+4\right)-1=\left(x+2\right)^2-1^2=\left(x+1\right)\left(x+3\right)\) (mình sửa lại)

b) \(x^2+8x-9=\left(x^2+8x+16\right)-25=\left(x+4\right)^2-5^2=\left(x-1\right)\left(x+9\right)\)

c) \(3x^2+6x-9=3\left[\left(x^2+2x+1\right)-4\right]=3\left[\left(x+1\right)^2-2^2\right]=3\left(x-1\right)\left(x+3\right)\)

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

 

6 tháng 7 2016

tik nhé Toán lớp 8

9 tháng 8 2018

mk ghi đáp án, còn lại bạn tự biến đổi

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

b) \(x^3+5x^2+8x+4=\left(x+1\right)\left(x+2\right)^2\)

c) \(\left(x+2\right)\left(x+3\right)\left(x+4\right)\left(x+5\right)-24=\left(x+1\right)\left(x+6\right)\left(x^2+7x+16\right)\)

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

e) \(x^4-7x^3+14x^2-7x+1=\left(x^2-4x+1\right)\left(x^2-3x+1\right)\)

9 tháng 8 2018

mk làm chi tiết theo yêu của của người hỏi đề:

a) \(2x^3-x^2+5x+3\)

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

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

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

b)  \(x^3+5x^2+8x+4\)

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

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

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

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

5 tháng 8 2018

\(a.x^4+4=\left(x^2\right)^2+2^2+4x^2-4x^2\\ =\left(x^2+2\right)^2-\left(2x\right)^2\\ =\left(x^2+2-2x\right)\left(x^2+2+2x\right)\\ b.4x^8+1=\left(2x^4\right)^2+1^2+4x^4-4x^4\\ =\left(2x^4+1\right)^2-\left(2x^2\right)^2\\ =\left(2x^4+1-2x^2\right)\left(2x^4+1+2x^2\right)\\ c.x^2-8x-9=x^2+x-9x-9\cdot1\\ =x\left(x+1\right)-9\left(x+1\right)\\ =\left(x-9\right)\left(x+1\right)\\ d.x^2+14x+48=x^2+6x+8x+6\cdot8\\ =x\left(x+6\right)+8\left(x+6\right)\\ =\left(x+8\right)\left(x+6\right)\)

....Good luck...!

8 tháng 12 2017

a) \(x^2+6x+9\)

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

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

b) \(10x-25-x^2\)

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

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

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

c) \(8x^3-\frac{1}{8}\)

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

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

d) \(\frac{1}{25}x^2-64y^2\)

\(=\left(\frac{1}{5}x\right)^2-\left(8y\right)^2\)

\(=\left(\frac{1}{5}x-8y\right)\left(\frac{1}{5}x+8y\right)\)

8 tháng 12 2017

a) \(x^2+6x+9=x^2+2.3.x+3^2\)\(=\left(x+3\right)^2\)

b)\(10x-25-x^2=-\left(x^2-10x+25\right)\)\(=-\left(x^2-2.5.x+5^2\right)=-\left(x+5\right)^2\)

c)\(8x^3-\frac{1}{8}=\left(2x\right)^3-\left(\frac{1}{2}\right)^3\)\(=\left(2x-\frac{1}{2}\right)\left(4x+x+\frac{1}{4}\right)\)

d)\(\frac{1}{25}x^2-64y^2=\left(\frac{1}{5}\right)^2-\left(8y\right)^2\)\(=\left(\frac{1}{5}-8y\right)\left(\frac{1}{5}+8y\right)\)

2 tháng 7 2017

=x3(x+2)-13x2+12x-26x+24

=x3(x+2)-x(13x-12)-2(13x-12)

=x3(x+2)-(13x-12)(x+2)

=(x+2)(x3-x-12x+12)

(x+2)[(x2-1)-12(x-1)]

=(x+2)[x(x-1)(x+1)-12(x-1)]

=(x+2)(x-1)[x(x+1)-12]

=(x+2)(x-1)(x2+x-12)

=(x+2)(x-1)(x2-3x+4x-12)

=(x+2)(x-1)[x(x-3)+4(x+3)]

=(x+2)(x-1)(x-3)(x+4)

2 tháng 7 2017

trong bài làm của mk có hàng k có dấu "=" chỗ đó có dâu"=" nha!

10 tháng 7 2019

\(g,x^2-2xy+y^2-9z^2=\left(x-y\right)^2-\left(3z\right)^2\)\(=\left(x-y+3z\right)\left(x-y-3z\right)\)

\(h,5x^4-20x^2=5x^2\left(x^2-4\right)=5x^2\left(x-2\right)\left(x+2\right)\)

\(i,7x^2-7y^2-14x+14y=7\left(x-y\right)\left(x+y\right)-14\left(x-y\right)\)

\(=\left(x-y\right)\left(7x+7y-14\right)=7\left(x-y\right)\left(x+y-2\right)\)

\(k,x^2+8x+3x+24=x\left(x+8\right)+3\left(x+8\right)=\left(x+8\right)\left(x+3\right)\)

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

\(n,x^6-y^6=\left(x^2-y^2\right)\left(x^4+x^2y^2+y^4\right)=\left(x-y\right)\left(x+y\right)\left(x^4+x^2y^2+y^4\right)\)