a: Ta có: \(4\left(x+1\right)^2+\left(2x+1\right)^2-8\left(x-1\right)\left(x+1\right)-11=0\)

\(\Leftrightarrow4x^2+8x+4+4x^2+4x+1-8x^2+8-11=0\)

\(\Leftrightarrow12x=-2\)

hay \(x=-\dfrac{1}{6}\)

b: Ta có: \(\left(x+3\right)^2-\left(x-4\right)\left(x+8\right)-1=0\)

\(\Leftrightarrow x^2+6x+9-x^2-4x+32-1=0\)

\(\Leftrightarrow2x=-40\)

hay x=-20

quá chuẩn luôn !!!!!!!!

NHỚ L.I.K.E cho mk nha

 a) (x+2)(x^2-2x+4)-x(x^2+2)=15 
<=> x^3 + 8 - x^3 - 2x = 15 
<=> -2x = 7 
<=> x = -7/2 

b) (x+3)^3-x(3x+1)^2+(2x+1)(4x^2-2x+1)=28 
<=> x^3 + 9x² + 27x + 27 - x(9x² + 6x + 1) + 8x^3 + 1 = 28 
<=> x^3 + 9x² + 27x + 27 - 9x^3 - 6x² - x + 8x^3 + 1 - 28 = 0 
<=> 3x² + 26x = 0 
<=> x(3x + 26) = 0 
Vậy x = 0 và x = -26/3 

c) (x^2-1)^3-(x^4+x^2+1)(x^2-1)=0 
<=> (x² - 1)[(x² -1)² - x^4 - x² - 1] = 0 
<=> (x-1)(x+1)(x^4 - 2x² + 1 - x^4 - x² - 1 ) = 0 
<=> -(x-1)(x+1)3x² = 0 
Vậy nghiệm là x = 1 ; -1 ; 0

Biết rồi đăng lên làm j

a)

\(\left(3x^2-x+1\right)\left(x-1\right)+x^2\left(4-3x\right)=\frac{5}{2}\)

\(\Leftrightarrow3x^3-x^2+x-3x^2+x-1+4x^2-3x^3=\frac{5}{2}\)

\(\Leftrightarrow2x-1=\frac{5}{2}\Leftrightarrow2x=1+\frac{5}{2}=\frac{7}{2}\Leftrightarrow x=\frac{7}{4}\)

b) 

\(4\left(x+1\right)^2+\left(2x-1\right)^2-8\left(x-1\right)\left(x+1\right)=11\)

\(\Leftrightarrow4\left(x^2+2x+1\right)+\left(4x^2-4x+1\right)-8\left(x^2-1\right)=11\)

\(\Leftrightarrow4x^2+8x+4+4x^2-4x+1-8x^2+8=11\)

\(\Leftrightarrow8x+4-4x+1+8=11\Leftrightarrow4x+13=11\Leftrightarrow4x=-2\Leftrightarrow x=-\frac{1}{2}\)

c)

\(\left(2x-1\right)^2+\left(x+3\right)^2-5\left(x+7\right)\left(x-7\right)=0\)

\(\Leftrightarrow4x^2-4x+1+x^2+6x+9-5\left(x^2-7^2\right)=0\)

\(\Leftrightarrow4x^2-4x+1+x^2+6x+9-5x^2+245=0\)

\(\Leftrightarrow-4x+1+6x+9+245=0\Leftrightarrow2x+255=0\Leftrightarrow x=-\frac{255}{2}\).

a ) ( 3x² - x + 1 ) ( x + 1 ) + x² ( 4 - 3x ) = 5/2

=> 3x³ + 3x² - x² - x + x + 1 + 4x² - 3x³ = 5/2

=> 6x² + 1 = 5/2

=> 6x² = 1,5

=> x² = 0,25

=> x = 0,5

a ) ( 3x 2 - x + 1 ) ( x + 1 ) + x 2 ( 4 - 3x ) = 5/2

=> 3x 3 + 3x 2 - x 2 - x + x + 1 + 4x 2 - 3x 3 = 5/2

=> 6x 2 + 1 = 5/2

=> 6x 2 = 1,5

=> x 2 = 0,25

=> x = 0,5 

=>4(x^2+2x+1)+4x^2-4x+1-8x^2-16x-8

=>4x^2+8x+4-4x^2-20x-7

=>-12x-3=11

=>-12x=14

=>x=-7/6

bạn phải trả lời mấy câu khác nữa mình mới cho

4.(\(x\) + 1)² + (2\(x\) - 1)² - 8.(\(x\) - 1)(\(x-1\) )= 11

4\(x^2\) + 8\(x\) + 4 + 4\(x^2\) - 4\(x\)  + 1 - 8\(x^2\) + 16\(x\)  - 8 = 11

(4\(x^2\) + 4\(x^2\) - 8\(x^2\)) + (8\(x\) - 4\(x\) + 16\(x\)) + (4 + 1 - 8) = 11

                               20\(x\)  - 3 = 11

                               20\(x\)        = 11 + 3

                               20\(x\)        = 14

                                   \(x\)        = \(\dfrac{7}{10}\)