Resuelve la siguiente ecuación cuadrática. \[ x^{2}-4 x=0 \] ( \( x_{1}=0, x_{2}=2 \) (C) \( x_{1}=0, x_{2}=-4 \) (a) \( x_{1}=0, x_{2}=-2 \) \( x_{1}=0, x_{2}=4 \)

Simplify the following expression. \[ \frac{x+8 y}{x-2 y} \div\left(\frac{1}{8 y}-\frac{1}{x+8 y}\right) \] \( \frac{x+8 y}{x-2 y} \div\left(\frac{1}{8 y}-\frac{1}{x+8 y}\right)=\square \) (Simplify your answer.)

Subtract. \[ \frac{3 x}{x^{2}-36}-\frac{2}{x+6} \]

\( \frac{\frac{\frac{2}{x}}{\frac{2}{x^{2}}+\frac{7}{x}}}{\frac{\frac{2}{x}}{\frac{2}{x^{2}}+\frac{7}{x}}=\square \text { (Simplify your answer.) }} \)

Reste \( 2 x^{2}-7 x-1 \) de la suma de \( x^{2}+9 x-4 \) y \( -5 x^{2}-7 x+10 \)

b) \( : \sqrt{x}=3 \)