8799. При каком значении х верна пропорция: a)=6= б) 4 x ; x 4 9 ; B) = 1 6 г) x 3x = 5 x x д) * = 7?

a) \(\frac{x}{4} = \frac{9}{x}\) \(x^2 = 36\) \(x = 6\) или \(x = -6\) б) \(\frac{x}{4} = \frac{x}{9}\) \(9x = 4x\) \(5x = 0\) \(x = 0\) B) \(\frac{x}{6} = \frac{3x}{18}\) \(18x = 18x\) \(x \in R\) г) \(\frac{x}{5} = \frac{3}{x}\) \(x^2 = 15\) \(x = \sqrt{15}\) или \(x = -\sqrt{15}\) д) \(\frac{x}{x} = \frac{7}{x}\) \(x = 7\) Ответ: a) x = 6; x = -6; б) x = 0; в) x - любое число; г) \(x = \sqrt{15}\); \(x = -\sqrt{15}\); д) x = 7