`(x-1)^2-2(x-1)(2x+1)+(2x+1)^2`

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

`=(-x-2)^2`

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

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

= (1-4x²)-x(x²-4)

=1-4x²-x³+4x

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

= ( 1 - 4 x² ) - x ( x² - 4 )

= 1 - 4 x² - x³ + 4x

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

\(=1-4x^2-x^3+4x\)

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

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

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

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

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

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

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

= 1 - 4x² - ( x² - 4)

= 1 - 4x² - x² + 4

= -5x² + 5

= - ( 5x² - 5 )

= - 5 (x² - 1)

Lần sau bạn cần chú ý viết đầy đủ yêu cầu đề bài.

Coi đây là bài toán rút gọn/ khai triển.

Ta có:

$(1+2x)(1-2x)-x(x+2)(x-2)$

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

$=1-4x^2-x(x^2-4)=-x^3-4x^2+4x+1$

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

\(=1-4x^2-x^3+4x\)

\(=-x^3+x^2-5x^2+5x-x+1\)

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

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

\(=\left(1-x\right)\left(x^2+\dfrac{2x.5}{2}+\dfrac{25}{4}-\dfrac{21}{4}\right)\)

\(=\left(1-x\right)\left(\left(x+\dfrac{5}{2}\right)^2-\dfrac{21}{4}\right)\)

\(=\left(1-x\right)\left(x+\dfrac{5}{2}-\dfrac{\sqrt{21}}{2}\right)\left(x+\dfrac{5}{2}+\dfrac{\sqrt{21}}{2}\right)\)

tìm x biết 2x+5 chia hết cho 3x-1

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

\(=1-4x-x^3-4x\)

\(=1-x^3-8x\)

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

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

\(=1-4x^2-x^3+4x\)

\(=1+x^2-5x^2-x^3+5x-x\)

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

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

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