Question

\(\dfrac{5}{x}+\dfrac{x^2}{3}=0\)

tìm x

Answer 1

`ĐKXĐ: x ne 0`

`\(\dfrac{5}{x}+\dfrac{x^2}{3}=0\\ \Leftrightarrow\dfrac{5.3}{3.x}+\dfrac{x^2.x}{3.x}=0\\ \Leftrightarrow\dfrac{15}{3x}+\dfrac{x^3}{3x}=0\\ \Leftrightarrow\dfrac{x^3+15}{3x}=0\\ \Rightarrow x^3+15=0\\ \Leftrightarrow x^3=-15\\ \Leftrightarrow x=\sqrt[3]{-15}\left(tm\right)\)

Vậy \(S=\sqrt[3]{-15}\)

Answer 2

\(\dfrac{5}{x}+\dfrac{x^2}{3}=0\)

\(ĐK:x\ne0\)

\(\Leftrightarrow\dfrac{15+x^3}{3x}=0\)

\(\Leftrightarrow15+x^3=0\)

\(\Leftrightarrow x^3=-15\)

\(\Leftrightarrow x=-\sqrt[3]{15}\)

Vậy \(S=\left\{-\sqrt[3]{15}\right\}\)