Question

[Nguyễn Hồng Nhung]

12) \(\dfrac{4x^2+16}{x^2+6}-\dfrac{3}{x^2+1}=\dfrac{5}{x^2+3}+\dfrac{7}{x^2+5}\)

13) x⁵ = x⁴ + x³ + x² + x + 2

Answer 1

[Nguyễn Lê Phước Thịnh]

12: \(\Leftrightarrow\left(\dfrac{4x^2+16-3x^2-18}{x^2+6}\right)=\left(\dfrac{3}{x^2+1}-1\right)+\left(\dfrac{5}{x^2+3}-1\right)+\left(\dfrac{7}{x^2+5}-1\right)\)

=>x²-2=0

hay \(x=\pm\sqrt{2}\)

13: \(\Leftrightarrow x^5-x^4-x^3-x^2-x-2=0\)

\(\Leftrightarrow x^5-2x^4+x^4-2x^3+x^3-2x^2+x^2-2x+x-2=0\)

=>x-2=0

=>x=2