\(\frac{x}{-15}=\frac{-60}{x}\)
\(\Rightarrow x^2=\left(-60\right)\left(-15\right)\)
\(\Rightarrow x^2=900\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=\sqrt{900}\\x=-\sqrt{900}\end{array}\right.\)
\(\Rightarrow\left[\begin{array}{nghiempt}x=30\\x=-30\end{array}\right.\)
Vậy x=30 ; x= - 30
\(=> x.x = -15.-60 => x^2 = 900 => x^2 = 30^2 => x=30 hoặc x=-30\)