Question

viết thành hằng đẳng thức 

a) 4x² - 4x +1

b) (3x +2)(2-3x)

c) (x-3)(x² +3x +9)

Answer 1

\(a)\)

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

\(b)\)

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

\(c)\)

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

Answer 2

\(a,4x^2-4x+1=\left(2x\right)^2-2.2x.1+1=\left(2x-1\right)^2\)

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

\(c,\left(x-3\right)\left(x^2+3x+9\right)=\left(x-3\right)\left(x^2+3x.1+3^2\right)=x^3-3^3\)

Answer 3

Trả lời:

a, 4x² - 4x + 1 = ( 2x )² - 2.2x.1 + 1² = ( 2x - 1 )²

b, ( 3x + 2 ) ( 2 - 3x ) = ( 2 + 3x ) ( 2 - 3x ) = 2² - ( 3x )² = 4 - 9x²

c, ( x - 3 ) ( x² + 3x + 9 ) = ( x - 3 ) ( x² + x.3 + 3² ) = x³ - 3³ = x³ - 27