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NV
23 tháng 7 2021

\(-8x^3+12x^2y-6xy^2+y^3=\left(-2x\right)^3+3.\left(-2x\right)^3y+3.\left(-2x\right).y^2+y^3\)

\(=\left(-2x+y\right)^3\) (hay \(\left(y-2x\right)^3\) tùy cách ghi)

Ta có: \(-8x^3+12x^2y-6xy^2+y^3\)

\(=-\left(8x^3-12x^2y+6xy^2-y^3\right)\)

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

29 tháng 11 2019

A

B(hơi sai)

28 tháng 10 2018

a) \(x^3+2x^2y+xy^2-4xz^2=x\left(x^2+2xy+y^2-4z^2\right)=x\left[\left(x+y\right)^2-\left(2z\right)^2\right]\)

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

b)\(-8x^3+12x^2y-6xy^2+y^3=y^3+3.y.\left(2x\right)^2-3.y^2.2x-\left(2x\right)^3\)\(=\left(y-2x\right)^3\)

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

d)\(x^4+64y^4=\left(x^2\right)^2+2.x^2.8y^2+\left(8y^2\right)^2-16x^2y^2=\left(x^2+8y^2\right)-\left(4xy\right)^2\)

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

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

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

h)\(3x^2-6xy+3y^2-12z^2=3\left(x^2-2xy+y^2-4z^2\right)=3\left[\left(x-y\right)^2-\left(2z\right)^2\right]\)

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

g)\(x^3-3x^2-9x+27=x^2\left(x-3\right)-9\left(x-3\right)=\left(x-3\right)\left(x^2-9\right)\)\(=\left(x-3\right)^2\left(x+3\right)\)

B2: \(x^3-5x=0\Rightarrow x\left(x^2-5\right)=0\Rightarrow\orbr{\begin{cases}x=0\\x^2-5=0\end{cases}}\)

\(\Rightarrow\orbr{\begin{cases}x=0\\x^2=5\end{cases}\Rightarrow\orbr{\begin{cases}x=0\\x=\pm\sqrt{5}\end{cases}}}\)\(\Rightarrow\orbr{\begin{cases}x=0\\x^2=5\end{cases}}\Rightarrow\orbr{\begin{cases}x=0\\\orbr{\begin{cases}x=\sqrt{5}\\x=-\sqrt{5}\end{cases}}\end{cases}}\)

15 tháng 9 2019

\(A=2^3-3.2^2.x+3.2.x^2-x^3\)

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

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

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

Bài 1: 

a: \(x^2\left(3x+2\right)=3x^3+2x^2\)

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

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

\(=3x^2-10x^2+9x-2\)

c: \(\left(3x+2\right)\left(9x^2-6x+4\right)-\left(x-3\right)\left(x+3\right)\)

\(=27x^3+8-x^2+9=27x^3-x^2+17\)

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

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

\(=2xz+2yz-z^2\)

29 tháng 7 2017

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

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

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

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

b)\(x^4+x^3+6x^2+5x+5\)

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

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

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

c)\(x^4-2x^3-12x^2+12x+36\)

\(=x^4-2x^3-6x^2-6x^2+12x+36\)

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

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

d)\(x^8y^8+x^4y^4+1\)

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

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

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

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

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

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

22 tháng 9 2019

bạn lm pb = cách nhẩm nghiệm đc không

4 tháng 8 2018

a) \(\dfrac{6x^2y^3-2x^2y+6xy}{6xy}\)

\(=\dfrac{6x^2y^3}{6xy}-\dfrac{2x^2y}{6xy}+\dfrac{6xy}{6xy}\)

\(=xy^2-\dfrac{x}{3}+1\)

b) \(\dfrac{4\left(x+y\right)^3}{2\left(x+y\right)}\)

\(=\dfrac{2\left(x+y\right).2\left(x+y\right)^2}{2\left(x+y\right)}\)

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

c) \(\dfrac{8x^3+27y^3}{2x+3y}\)

\(=\dfrac{\left(2x\right)^3+\left(3y\right)^3}{2x+3y}\)

\(=\dfrac{\left(2x+3y\right)\left[\left(2x\right)^2-2x.3y+\left(3y\right)^2\right]}{2x+3y}\)

\(=4x^2-6xy+9y^2\)

d) \(\dfrac{48x^4y^3-12x^2y^5+6x^2y^2}{3x^2y^2}\)

\(=\dfrac{48x^4y^3}{3x^2y^2}-\dfrac{12x^2y^5}{3x^2y^2}+\dfrac{6x^2y^2}{3x^2y^2}\)

\(=16x^2y-4y^3+2\)

1 tháng 10 2017

Giải:

3x2- 9x2+12x2y2 = 3x2(1-3+4y2)

x2yz+xy2z+xyz2 = xyz(x+y+z)

ax+ay = a(x+y)

2x+4y2 = 2(x+2y2)

2x2+6x = 2x(x+3)

5x10-10x6 = 5x6(x4-2)

bx2-by = b(x2-y)

10xy2 -10x2y3 = 10xy2(1-xy2)

64xy-96x2y+48x3y-8x4y = 8xy(8-12x+6x2-x2)

17x3y-34x2y2 = 17x2y(x-2y2)

12x2-18xy2-30y3 = 6(2x2-3xy2-5y3)

7x+7y = 7(x+y)

a2x+a2y = a2(x+y)

36x6y4-27x5y5 = 9x5y4(4x-3y)

6x4-9x3 = 3x3(2x-3)

5x2y-15x2y2 = 5x2y(1-3y)

abc2+a2bc-ab2c = abc(c+a-b)

Chúc bạn học tốt!

1 tháng 10 2017

cảm ơn bạn