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

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

13 tháng 10 2019

\(e,-5x+x^2-14\)

\(=x^2+2x-7x-14\)

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

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

\(f,x^3+8+6x\left(x+2\right)\)

\(=\left(x+2\right)\left(x^2+2x+4\right)+6x\left(x+2\right)\)

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

\(g,15x^2-7xy-2y^2\)

\(=15x^2+3xy-10xy-2y^2\)

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

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

\(h,3x^2-16x+5\)

\(=3x^2-x-15x+5\)

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

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

13 tháng 10 2019

\(a,x^3+2x^2y+xy^2=x\left(x^2+2xy+y^2\right)\)

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

\(b,4x^2-9y^2+4x-6y\)

\(=4x^2+4x+1-\left(9y^2+6y+1\right)\)

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

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

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

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

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

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

\(d,x^2+4x-12\)

\(=x^2-2x+6x-12\)

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

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

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

5 tháng 11 2018

a) \(x^{12}-3x^6+1\)

\(=\left(x^6\right)^2-2\cdot x^6\cdot1+1^2-x^6\)

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

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

5 tháng 11 2018

b) \(x^4+6x^3+7x^2-6x+1\)

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

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

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

12 tháng 8 2020

a) 3( x - y ) - 5x( y - x )

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

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

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

b) x3 + 2x2y + xy2 - 9x

= x( x2 + 2xy + y2 - 9 )

= x[ ( x + y )2 - 32 ]

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

c) 14x2y - 21xy2 + 28x2y2

= 7xy( 2x - 3y + 4xy )

12 tháng 8 2020

                                              Bài giải

\(a,\text{ }3\left(x-y\right)-5x\left(y-x\right)\)

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

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

\(b,\text{ }x^3+2x^2y+xy^2-9x\)

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

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

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

\(c,\text{ }14x^2y-21xy^2+28x^2y\)

\(=7xy\left(2x-3y+4x\right)\)

\(=7xy\left(6x-3y\right)\)

21 tháng 9 2017

b) \(49y^2-x^2+6x-9\)

\(=49y^2-\left(x^2-6x+9\right)\)

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

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

a) \(a^2-9+6x-x^2\)

\(=a^2-\left(9-6x+x^2\right)\)

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

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

31 tháng 7 2018

c, \(2x^2+x-3=x\left(2x-3\right)\)

d, \(6x^2-x-15=x\left(6x-15\right)\)

TK MIK NHA

31 tháng 7 2018

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