Question

tim x

x/3 =3/x

8/5=-12/x

x/-4=-4/x

Answer 1

\(\frac{x}{3}=\frac{3}{x}\)

\(\Leftrightarrow9=x^2\)

\(\Leftrightarrow x=\sqrt{9}\)

\(\Leftrightarrow x\in\left\{-3;3\right\}\)

\(\frac{8}{5}=\frac{-12}{x}\)

\(\Leftrightarrow8x=-60\)

\(\Leftrightarrow x=\frac{-15}{2}\)

\(\frac{x}{-4}=\frac{-4}{x}\)

\(\Leftrightarrow-x^2=-16\)

\(\Leftrightarrow x^2=16\)

\(\Leftrightarrow x=\sqrt{16}\)

\(\Leftrightarrow x\in\left\{-4;4\right\}\)

Answer 2

câu 1 : x = 3

vì 3/3 cũng = 3/3

Answer 3

\(\frac{x}{3}=\frac{3}{x}\Rightarrow x^2=9\Rightarrow x=\pm9\)

\(\frac{8}{5}=\frac{-12}{x}\Rightarrow x=\frac{5.\left(-12\right)}{8}=-7,5\)

\(\frac{x}{-4}=\frac{-4}{x}\Rightarrow x^2=16\Rightarrow x=\pm4\)