Two people are in a boat that is capable of a maximum speed of \( 5 \mathrm{~km} / \mathrm{hr} \) in still water. The people wish to cross a river 1 km wide to a point directly across from their starting point. If the speed of the water in the river is \( 4 \mathrm{~km} / \mathrm{hr} \) , what is the minimum time required for the crossing? (A) \( \frac{1}{9} \mathrm{hr} \) (B) \( \frac{1}{5} \mathrm{hr} \) (C) \( \frac{1}{4} \mathrm{hr} \) (D) \( \frac{1}{3} \mathrm{hr} \)

Qual é o valor de \( |5+\sqrt{8}| \) ?

Las pliginas de un libro deben medir cada una \( 600 \mathrm{~cm}^{2} \) de área. Sus márgenes laterales y el inferior miden 2 cm y el superior mide 3 cm . Hallar, si es posible, las dimensiones de la hoja que tenga área máxima de impresión.

Actividad: Obtener las asíntotas (verticales \( y \) horizontales) de las siguientes funciones. Luego, graficar para comprobar los resultados obtenidos. \( \begin{array}{ll}\text { a) } f(x)=\frac{x^{2}}{x^{2}-4} & \text { b) } f(x)=\frac{x^{3}+x}{x^{2}-1} \\ \text { c) } f(x)=\frac{x-3}{x-2} & \text { d) } f(x)=\frac{x^{2}}{x^{2}-9} \\ \text { e) } f(x)=\frac{4}{x^{2}-5 x+6} & \text { f) } f(x)=\frac{1}{(x+2)^{2}} \\ \text { g) } f(x)=\frac{4 x+1}{x-2} & \text { h) } f(x)=\frac{4 x+1}{x^{2}-5 x+6}\end{array} \)

13. A printing error in a math book removed the brackets and parentheses from a numerical expression. Rewrite the expression \( 3^{2}+7 x 4+5 \) with parentheses so that it is equivalent to 69 .

What was the effect of the American Revolution on the numbers of free African Americans in the former colonies?