8. \( [5-68 . c] \quad \) Write the explicit rule and determine the 100 th term for the given sequence. \( \quad 24,19,14, \ldots \)

5 State which consecutive whole numbers are either side of: \( \begin{array}{llll}\text { a } \sqrt{29} & \text { b } \sqrt{40} \\ \text { e } \sqrt{85} & \text { f } \sqrt{103} & \text { o } & \sqrt{71}\end{array} \)

Calcula las siguientes potencias: \( \begin{array}{ll}\text { a) } 3^{-4}=\frac{\square}{\square} & \text { b) }(3 / 4)^{-2}=\frac{\square}{\square}\end{array} \)

5 State which consecutive whole numbers are either side of: \( \begin{array}{lll}\text { a } \sqrt{29} & \text { b } \sqrt{40} & \text { c } \\ \text { 7II }\end{array} \)

The postal service of a country charges \( \$ 0.36 \) postage for a letter weighing up to 1 ounce, plus \( \$ 0.26 \) for each additional ounce up to 5 ounces. Letters weighing more than 5 ounces do not qualify for these rates. \( C(x)=\left\{\begin{array}{ll}\$ \square & \text { if } 0<x \leq 1 \\ \text { (a) Write a piecewise-defined function } C \text { for the postage charged for a letter weighing } x \text { ounces. } \\ \$ \square & \text { if } 3<x \leq 4 \\ \$ \square & \text { if } 4<x \leq 5\end{array}\right. \)

\( \frac{4}{1\times 2}+\frac{4}{2\times 3}+\frac{4}{3\times 4}+...+\frac{4}{23\times 24} \)