Giai phuong trinh: `x^6-5x^3-24=0`

2 bình luận về “Giai phuong trinh: `x^6-5x^3-24=0`”

1. Ta có:

   x^6+3x^3-8x^3-24=0⇔x^3(x^3+3)-8(x^3+3)=0

   $⇔(x^3+3)(x^3-8)⇔\left[\begin{matrix} x^3=-3\\ x^3=8\end{matrix}\right.⇔\left[ \begin{array}{l}x=\sqrt[3]{-3}}\\x=2\end{array} \right.$

   Vậy S\in{\sqrt[3]{-3};2}

    

   Trả lời
2. x^6 – 5x^3 – 24 = 0

   <=> x^6 + 3x^3 – 8x^3 – 24 = 0

   <=> (x^6 + 3x^3) – (8x^3 + 24) = 0

   <=> x^3 (x^3 + 3) – 8 (x^3 + 3) = 0

   <=> (x^3 – 8)(x^3 + 3) = 0

   <=> \(\left[ \begin{array}{l}x^3 = 8\\x^3 = -3\end{array} \right.\) 

   <=> \(\left[ \begin{array}{l}x=2\\x= \sqrt[3]{-3}\end{array} \right.\) 

   Vậy S = {\sqrt[3]{-3}; 2}

   (Chúc bạn học tốt :))

   Trả lời