a) \(\left(x+3\right)^2-x\left(3x+1\right)^2+\left(2x+1\right)\left(4x^2-2x+1\right)-2x^2=54\)

=> x² + 6x + 9 - x(9x² + 6x + 1) + (2x)³ + 1³ - 2x² = 54

=> x² + 6x + 9 - 9x³ - 6x² - x + 8x³ + 1 - 2x² = 54

=> (-9x³ + 8x³) + (x² - 6x² - 2x²) + (6x - x) + (9 + 1) = 54

=> -x³ - 7x² + 5x + 10 = 54

=> -(x³ + 7x² - 5x - 10) = 54

=> phương trình vô nghiệm

b) (x + 3)³  - (x - 3)(x² + 3x + 9) + 6(x + 1)² + 3x = -33

=> x³ + 9x² + 27x + 27 - (x³ - 3³) + 6(x² + 2x + 1) + 3x = -33

=> x³ + 9x² + 27x + 27 - x³ + 27 + 6x² + 12x + 6 + 3x = -33

=> (x³ - x³) + (9x² + 6x²) + (27x + 12x + 3x) + (27 + 27 + 6) = -33

=> 15x² + 42x +  60 = -33

=> 15x² + 42x + 60 + 33 = 0

=> 15x² + 42x + 93 = 0

=> 3(5x² + 14x + 31) = 0

=> 5x² + 14x + 31 = 0

=> không tìm được x

Chia nhỏ ra ik ạ

\(\left(2x+3\right)\left(2x-3\right)-4x\left(x+5\right)=4x^2-9-4x^2-20x=-20x-9\)

\(5x\left(x-3\right)+\left(x-2\right)^2=5x^2-15x+x^2-4x+4=6x^2-19x+4\)

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

\(\left(x-3\right)\left(x^2-6x+9-x^2-3x-9\right)+9x^2+12x+39=0\)

\(\Leftrightarrow-9x\left(x-3\right)+9x^2+12x+39=0\)

\(\Leftrightarrow39x+39=0\Rightarrow x=-1\)

Câu a bạn tính ra rồi giải nha

a: \(\left(x+3\right)^3-x\left(2x+1\right)^2+\left(2x+1\right)\left(4x^2-2x+1\right)-3x^2=54\)

\(\Leftrightarrow x^3+9x^2+27x+27+8x^3+1-3x^2-x\left(2x+1\right)^2=54\)

\(\Leftrightarrow9x^3+6x^2+27x+28-4x^3-4x^2-x-54=0\)

\(\Leftrightarrow5x^3+2x^2+26x-26=0\)

\(\Leftrightarrow x\simeq0,835\)

b: \(\left(x-3\right)^3-\left(x-3\right)\left(x^2+3x+9\right)+6\left(x+1\right)^2+3x^2=33\)

\(\Leftrightarrow x^3-9x^2+27x-27-x^3+27+6x^2+12x+6+3x^2=33\)

\(\Leftrightarrow39x-21=33\)

=>39x=54

hay x=18/13

\(a.x\left(x-5\right)\left(x+5\right)-\left(x+2\right)\left(x^2-2x+4\right)=3\)

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

\(\Leftrightarrow x^3-25x-x^3-8=3\)

\(\Leftrightarrow x^3-x^3-25x=8+3\)

\(\Leftrightarrow x=\frac{11}{-25}\)

Vậy x có nghiệm là \(\frac{-11}{25}.\)

\(\)