a) ( a   +   4 ) 3 .                        b) ( 2   –   b ) 3 .

c) ( m − 2 ) 2 − 2 3 .                 d) 2 a 3 − 2 b 3 .

xl chuyển hộ mk "bình phương" thành "lập phương" nha

\(=\left(\dfrac{2}{3}a\right)^3-3.\left(\dfrac{2}{3}\right)^2a^2.2b+3.\dfrac{2}{3}a.4b^2-\left(2b\right)^3=\left(\dfrac{2}{3}a-2b\right)^3\)

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

Bài 1: 

c: \(\left(-5x-y\right)^3=-125x^3-75x^2y-15xy^2-y^3\)

h: \(\left(3y-2x^2\right)^3=27y^3-54y^2x^2+36yx^4-8x^6\)

Bài 1:

c. (-5x - y)³ = -125x³ - 50x²y - 10xy² - y³

d. (3y - 2x²)³ = 27y³ - 18x²y² + 24xy⁴ - 8x⁶

(x + y)³ = x³ + 3x²y + 3xy² + y³

(x - y)³ = x³ - 3x²y + 3xy² - y³

 Chúc bạn học tốt

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

\(a,x^3+6x^2y+12xy^2+8y^3\\ =x^3+3.2x^2+3.2^2.x+\left(2y\right)^3\\ =\left(x+2y\right)^3\)

\(b,x^3-3x^2+3x-1\\ =x^3-3x^2.1+3x.1^2-1^3\\ =\left(x-1\right)^3\)

a) \(x^3+6x^2y+12xy^2+8y^3\)

\(=x^3+3\cdot x^2\cdot2y+2\cdot x\cdot\left(2y\right)^2+\left(2y\right)^3\)

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

b) \(x^3-3x^2+3x-1\)

\(=x^3-3\cdot x^2\cdot1+3\cdot x\cdot1^2-1^3\)

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

Bài giải:

a) – x³ + 3x²– 3x + 1 = 1 – 3 . 1² . x + 3 . 1 . x² – x³

= (1 – x)³

b) 8 – 12x + 6x² – x³ = 2³ – 3 . 2². x + 3 . 2 . x² – x³

= (2 – x)³

a) \(-x^3+3x^2-3x+1=1-3x+3x^2-x3\)

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

b) \(8-12x+6x^2-x^3\) \(=2^3-3.2^2.x+3.2.x^2-x^3\)

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

a) -x³+3x²-3x+1=1-3x+3x²-x³

=(1-x)³

b) 8-12x+6x²-x³=(2-x)³

HĐT số 4: \(\left(A+B\right)^3=A^3+3A^2B+3AB^2+B^3\)

__________

\(x^3+3x^2+3x+1\)

\(=x^3+3\cdot x^2\cdot1+3\cdot x\cdot1^2+1^3\)

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

`x^3 +3x^2+3x+1`

`= x^3 + 3*x^2*1 +3*x*1^2 +1^3`

`=(x+1)^3`

x^3 + 3x^2 + 3x + 1

<=> x^3 + 3x^2.1 + 3x.1^2 + 1^3

<=> (x + 1) ^3

8 – 12x + 6x2 – x3

= 23 – 3.22.x + 3.2.x2 – x3

= (2 – x)3 (Áp dụng HĐT (5) với A = 2 và B = x)