Answer:

Step-by-step explanation:
To find the rate of change of temperature with respect to distance at the point (3, 1) in the x-direction and the y-direction we need to find the Directional Derivative of T(x,y). The definition of the directional derivative is given by:

Where i and j are the rectangular components of a unit vector. In this case, the problem don't give us additional information, so let's asume:


So, we need to find the partial derivative with respect to x and y:
In order to do the things easier let's make the next substitution:

and express T(x,y) as:

The partial derivative with respect to x is:
Using the chain rule:

Hence:

Symplying the expression and replacing the value of u:

The partial derivative with respect to y is:
Using the chain rule:

Hence:

Symplying the expression and replacing the value of u:

Therefore:

Evaluating the point (3,1)

First, find out how many pounds in a ton. 2000 pounds are in one ton. It is 70 cents for 1 pounds, multiply that by 2000 to see how much it costs for a ton. It would get you $1,400. Next, multiply 1,400 by 5 to see how much it is for 5 tons. It cost approximately 7,000 dollars.
Answer: a)
are needed to travel 8 miles
b) Town X and town Y are 15 miles apart.
Step-by-step explanation:
Given : Gasoline used to travel 5 miles = 3t gallons
a) To find: Gasoline used to travel 8 miles = ?
Using unitary method:
If Gasoline used to travel 5 miles = 3t gallons
Thus Gasoline used to travel 8 miles = 
are needed to travel 8 miles
b) when 3t gallons of gasoline are used , distance covered = 5 miles
Thus when 9t gallons of gasoline are used , distance covered = 
Thus town X and town Y are 15 miles apart.
Answer:
2.5 dB/100 ft
Explanation:
If 5 dB was lost after 200 ft of cable and 100 ft is half of 200 ft, then the rate of loss should be 2.5 dB per 100 ft.
Step-by-step explanation: