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16 tháng 12 2018

d) \(x^4-5x^2+4\)

Đặt \(x^2=t\).Ta có:

\(x^4-5x^2+4=t^2-5t+4\)

\(t^2-t-4t+4=\left(t^2-t\right)-\left(4t-4\right)\)

\(=t\left(t-1\right)-4\left(t-1\right)=\left(t-1\right)\left(t-4\right)\)

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

16 tháng 12 2018

a) \(x^3-3x^2-4x+12\)

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

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

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

b) \(2x^2-2y^2-6x-6y\)

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

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

\(=\left(x+y\right)\left[2\left(x-y\right)-6\right]\)

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

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

c) \(x^3+3x^2-3x-1\)

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

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

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

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

d) \(x^4-5x^2+4\)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

16 tháng 7 2018

a)   \(x^3-2x^2-6x+12\)

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

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

\(=\left(x-2\right)\left(x-\sqrt{6}\right)\left(x+\sqrt{6}\right)\)

b)  \(x^4-7x^2+12\)

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

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

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

\(=\left(x-\sqrt{3}\right)\left(x+\sqrt{3}\right)\left(x-2\right)\left(x+2\right)\)

c)  \(x^2-5x+4\)

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

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

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

d)  \(3x^2+5x+2\)

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

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

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

e)  \(x^3-x+3x^2y+3xy^2+y^3-y\)

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

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

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

11 tháng 12 2018

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

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

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

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

Tham khảo nhé~

21 tháng 12 2017

A . 5(x-y)-y(x-y)

=(x6-y)(5-y)

B . x^2 - xy - 8x+8y

=(x^2-xy)-(8x-8y))

=x(x-y) - 8(x-y)

C. x^2-10x+25 - y^2

=(x^2 - 10x + 25 ) - y^2

=(x-5)^2 - y^2

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

D . x^3 - 3x^2-4x+12

=(x^3 - 3x^2 ) - (4x - 12)

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

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

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

D . 2x^2-2y^2- 6x-6y

=(2^x - 2y^2) - (6x+ 6y)

=2(x^2 - y^2) - 6(x+y)

=2(x+y)(x-y) - 6(x+y)

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

E . x^3 - 3x^2 + 3x - 1

=(x-1)^3

D.x^2+3x+2

=x^2+2x+x+2

=(x^2+2x)+(x+2)

=x(x+2)+(x+2)

=(x+2)(x+1)

21 tháng 12 2017

Sai vài chỗ nha bạn! :)

14 tháng 8 2016

a,3x-6y

=3(x-2y)

b,=x^2(2/5+5x+y)

k đúng cho mk nhé bạn

Câu 2 nha

\(a,x^4+2x^3+x^2\)

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

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

\(c,x^2-x+3x^2y+3xy^2+y^3-y\)

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

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

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

8 tháng 9 2017

a) x^3−3x^2−4x+12

=(x^3-3x^2)-(4x-12)

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

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

b) x^4-5x^2+4=x^4-x^2-4x^2+4

=(x^4-x^2) - ( 4x^2-4)

=x^2(x^2-1) - 4(x^2-1)

=(x^2-1)(x^2-4)

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

c) (x+y+z)^3-x^3-y^3-z^3

=x^3+y^3+z^3+3x^2yz+3xy^2z+3xyz^2-x^3-y^3-z^3

=3x^2yz+3xy^2z+3xyz^2

3xyz(x+y+z)