If latex: \{a_i: i\in i\} is a collection of open subsets of latex: \mathbb{r} , then latex: \cup_{i\in i}a_i is open in latex: \mathbb{r}

(can this be proved without the concept of the open ball from topology)

Aheated piece of metal cools according to the function c(x) = (.5)x ? 7, where x is measured in hours. a device is added that aids in cooling according to the function h(x) = ? x ? 2. what will be the temperature of the metal after two hours?

40 describe the outliers from the scatter plot.

Astore sells two types of radios. one type sells $87 and the other for $119. if 25 were sold and the sales were $2495, how many of the $87 radios were sold a) 5 b) 20 c) 15 d)10