<PRE><B>Question 53661</B>
&lt;pre&gt;&lt;font size=5&gt;&lt;b&gt;find the linear depreciation equation for the TV in the 
advertisement shown below: 
Three (3) years old flat screen TV;
Matrix surround sound with PIP remote
Bought new-$7,500.00; Asking $2,500.00

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When it was bought new, the time was = 0 years and the 
value was $7500.

Now that it is being sold, the time is = 3 and the value 
is $2500.

This amounts to finding the equation of a line that 
passes through the two points (0, 7500) and (3, 2500), 
where x represents the time and y represents the value of 
the TV.

     y&lt;sub&gt;2&lt;/sub&gt; - y&lt;sub&gt;1&lt;/sub&gt;
m = ---------  
     x&lt;sub&gt;2&lt;/sub&gt; - x&lt;sub&gt;1&lt;/sub&gt;

where (x&lt;sub&gt;1&lt;/sub&gt;,y&lt;sub&gt;1&lt;/sub&gt;) = (0,7500) and (x&lt;sub&gt;2&lt;/sub&gt;,y&lt;sub&gt;2&lt;/sub&gt;) = (3,2500)

     2500 - 7500     -5000
m = ------------- = -------
        3 - 0          3

Now use the point-slope formula:

  y - y&lt;sub&gt;1&lt;/sub&gt; = m(x - x&lt;sub&gt;1&lt;/sub&gt;)

y - 7500 = -5000/3(x - 0)

y - 7500 = (-5000/3)x

       y = 7500 - (5000/3)x

We now would probably change y to V for value, and
x to t for time

       V = 7500 - (5000/3)t  where 0 &lt;u&gt;&lt;&lt;/u&gt; t &lt;u&gt;&lt;&lt;/u&gt; 4.5 

Edwin&lt;/pre&gt;</PRE>