khó quá

\(p^3-27p-54=\left(p^2-3p-18\right)\left(p+13\right)\)

\(=\left(p-6\right)\left(p+3\right)^2\)Vậy hả hay như nào ? 

Ta có : \(\left(p-6\right)\left(p+3\right)^2=0\)

\(\Rightarrow\orbr{\begin{cases}p=6\\p=-3\end{cases}}\)Hay như nào ? chưa hiểu đề lắm ! 

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

x³ - y³ - 3x² + 3x - 1

= x³ - 3x² + 3x - 1 - y³

= (x³ - 3x² + 3x - 1) - y³

= (x - 1)³ - y³

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

= (x - 1 - y)(x² - 2x + 1 + xy - y + y²)

\(=\left(3x+1\right)^3+\dfrac{1}{3}\left(3x+1\right)=\left(3x+1\right)\left(9x^2+6x+1+\dfrac{1}{3}\right)\\ =\left(3x+1\right)\left(9x^2+6x+\dfrac{4}{3}\right)\)

12) \(\sqrt{11+2\sqrt{30}}=\sqrt{\left(\sqrt{6}\right)^2+2.\sqrt{6}.\sqrt{5}+\left(\sqrt{5}\right)^2}\)

\(=\sqrt{\left(\sqrt{6}+\sqrt{5}\right)^2}=\sqrt{6}+\sqrt{5}\)

\(=\sqrt{6+2\cdot\sqrt{6}\cdot\sqrt{5}+5}\)

\(=\sqrt{\left(\sqrt{6}+\sqrt{5}\right)^2}=\sqrt{6}+\sqrt{5}\)

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

\(=x^2-x-2x+2\)

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

\(=\left(x-1\right).\left(x-2\right)\)

Học tốt nhé

x^2 - 3x + 2

= x^2 - 2x - x + 2

= x(x-2) - (x-2)

= (x-2)(x-1)

hok tốt

Sai đề bài rồi bạn ơi

\(\Delta=27^2-4.168=57>0\)

pt có 2 nghiệm pb 

\(x=\dfrac{27\pm\sqrt{57}}{2}\)

7. A = (x + y)^2 - 4y^2

= (x + y - 2y)(x + y + 2y)

= (x - y)(x + 3y)

2. x^4 + 4

= x^4 + 4x^2 + 4 - 4x^2

= (x^2 + 2)^2 - (2x)^2

= (x^2 + 2x + 2)(x^2 - 2x + 2)

3. 4x^4 + 16

= 4(x^4 + 4)

= 4(x^2 + 2x + 2)(x^2 - 2x + 2)