PLEASE HELP (:
A student is planning a camping trip and wants to take a few electronic device along. Her flexible portable solar panel converts electromagnetic energy from the sun into electrical energy at a rate of 21,600 J/h. Which devices could she charge with it at one time?

a. All three devices
b. The AA/AAA battery charger
c. The PDA charger or the cell phone charger separately, but not both together
d. Both the cell phone charger and the PDA charger together

Graph the system: f(x)= 3/x-2; f(x)= 1/2x + 2

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?

1- is the product of two rational numbers irrational or rational? first, make a hypothesis by multiplying two rational numbers. then, use variables such as x=a/b and y=c/d and the closure property of integers to prove your hypothesis. 2- what do you think the product of a nonzero rational number and an irrational number is? is it rational or irrational? make use of variables, the closure property of integers, and possibly a proof by contradiction to prove your hypothesis. 3- why do we have to specify that the rational number must be nonzero when we determine what the product of a nonzero rational number and an irrational number is? if the rational number were 0, would it give us the same result we found in part b?