D) 64x^3-1/8y^3

= (4x)^3 + (1/2y)^3

= ( 4x + 1/2y ) [ (4x)^2 - 4x.1/2y + (1/2y)^2 ]

E) 125x^6-27y^9

( câu này mik chưa rõ nên vx chưa tek giải cho bn )

HOk tốt nhé

a.x^3 + 8

= x^3 + 2^3

= ( x+2) ( x^2 - x.2+2^2)

b/27-8y^3

3^3 - (2y)^3

= ( 3 - (2y))(3^2 + 3.2y + (2y)^2)

c/ y^6 + 1

= (y^3)^3 + 1 ^3

= (y^3 + 1)((y^3)^2 - y^3.1 + 1^2

Cảm ơn bn nhìu ><

a. \(\left(3b+\dfrac{5a}{6}\right)^2\)

= \(9b^2+15ab+\dfrac{25a^2}{36}\)

b. (5x - y)²

= 25x² - 10xy + y²

c. (2a + b - 5)(2a - b + 5)

= 4a² - (b - 5)²

d. \(\left(x^2+\dfrac{2}{5y}\right)\left(x^2-\dfrac{2}{5y}\right)\)

= \(x^4-\dfrac{4}{25y^2}\)

a) \(\left(2x+1\right)^3\)

\(=\left(2x\right)^3+3.\left(2x\right)^2.1+3.2x.1+1\)

\(=8x^3+12x^2+6x+1\)

b) \(\left(x-3\right)^3\)

\(=x^3-3.x^2.3+3.x.3^2-3^3\)

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

Bài 2: 

a: \(x^3+15x^2+75x+125=\left(x+5\right)^3\)

b: \(1-15y+75y^2-125y^3=\left(1-5y\right)^3\)

c: \(8x^3+4x^2y+\dfrac{3}{2}xy^2+8y^3=\left(2x+2y\right)^3\)

a. (3a + 1)³

= 27a³ + 27a² + 9a + 1

3) \(A=2017.2019=\left(2018+1\right)\left(2018-1\right)=2018^2-1\)

\(\Rightarrow A< B\)

Bài 1:

a)  \(x^2+2y^2+2xy-2y+2=0\)

\(\Leftrightarrow\)\(\left(x+y\right)^2+\left(y-1\right)^2+1=0\)

Ta thấy  \(VT>0\)

suy ra phương trình vô nghiệm

b)  \(x^2+y^2-4x+4=0\)

\(\Leftrightarrow\)\( \left(x-2\right)^2+y^2=0\)

\(\Leftrightarrow\)\(\hept{\begin{cases}x-2=0\\y=0\end{cases}}\)

\(\Leftrightarrow\)\(\hept{\begin{cases}x=2\\y=0\end{cases}}\)

Vậy...

Bài 2:

a)  \(8y^3-125x^3=\left(2y-5x\right)\left(4y^2+10xy+25y^2\right)\)

b)  \(a^6-b^6=\left(a^3-b^3\right)\left(a^3+b^3\right)\)

\(=\left(a-b\right)\left(a+b\right)\left(a^2+ab+b^2\right)\left(a^2-ab+b^2\right)\)

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

Bài 3:

\(A=2017.2019=\left(2018-1\right)\left(2018+1\right)=2018^2-1< 2018^2=B\)

Vậy  \(A< B\)

a,3x³y³-15x²y²=3x²y²(xy-5)

b,2x(x-5y)+8y(5y-x)=2x(x-5y)-8y(x-5y)=(x-5y).(2x-8y)

c,(3x-1)²-16=(3x-1)²-4²=(3x-1+4)(3x-1-4)=(3x+3)(3x-5)

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

e,125x³+1=(5x)³+1³=(5x+1)(25x²-5x.1+1²)

f,x³+6x²y+12xy²+8y³=x³+3.x².2y+3.x.(2y)²+(2y)³=(x+2y)³