Question

Tìm x:

x⁴ + 6x³ + 11x² + 6x +1 = 0

Answer 1

x⁴+6x³+11x²+6x+1=0

x⁴+6x³+9x²+(2x²+6x)+1=0

(x²+3x+1)²=0

=>x²+3x+1=0

\(\Delta=b^2-4ac=3^2-4.1.1=5\)

=> \(\sqrt{\Delta}=\sqrt{5}\)

x₁=\(\frac{-b+\sqrt{\Delta}}{2a}=\frac{-3+\sqrt{5}}{2}\)

x₂=\(\frac{-b-\sqrt{\Delta}}{2a}=\frac{-3-\sqrt{5}}{2}\)

Answer 2

x⁴ + 6x³ + 11x² + 6x + 1 = 0

\(\Leftrightarrow\)(x⁴ + 6x³ + 9x²) + (2x² + 6x) + 1 = 0

\(\Leftrightarrow\)(x² + 3x + 1)² = 0

\(\Leftrightarrow\)x² + 3x + 1 = 0

Bạn làm tiếp nhé