4. Rachel has 3000 feet of fencing to enclose a rectangular field for her horses. One side of the field lies along the river, so only three sides require fence material.
a. Express the area A of the rectangle as a function of the width x of the rectangle.
b. What is the domain of A?
c. Use a graphing calculator to find the value of x that produces the largest area.

Adecibel is a logarithmic unit that can be used to measure the intensity of a sound. the function y = 10logx gives the intensity of a sound in decibels, where x is the ratio of the intensity of the sound to a reference intensity. the reference intensity is generally set at the threshold of hearing. use the graphing utility to graph the decibel function.a whisper has a sound intensity of 30 decibels. use your graph to you complete the following statement. the sound intensity of a whisper is times the reference intensity.