SOLUTION: A factory owner buys a new machine for $21,000. After eight years, the machine has a salvage value of $3000. Find a formula for the value of the machine after t years, where 0 &#88

Algebra ->  Coordinate Systems and Linear Equations  -> Linear Equations and Systems Word Problems -> SOLUTION: A factory owner buys a new machine for $21,000. After eight years, the machine has a salvage value of $3000. Find a formula for the value of the machine after t years, where 0 &#88      Log On


   

Question 1097603: A factory owner buys a new machine for $21,000. After eight years, the machine has a salvage value of $3000. Find a formula for the value of the machine after t years, where 0 ≤ t ≤ 8.
Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
I assume it's a straight line relation
Plot +v+ on vertical axis
Plot +t+ on horizontal axis
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The slope is +%28+3000+-+21000+%29+%2F+%28+8+-+0+%29+
slope = +-18000%2F8+
slope = +-2250+
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Use the general point-slope formula
+%28+v+-+3000+%29+%2F+%28+t+-+8+%29+=+-2250+
+v+-+3000+=+-2250%2A%28+t+-+8+%29+
+v+-+3000+=+-2250t+%2B+18000+
+v+=+-2250t+%2B+21000+
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check:
When +t=0+
+v+=+21000+
OK
When +t=8+
+v+=+-2250%2A8+%2B+21000+
+v+=+-18000+%2B+21000+
+v+=+3000+
OK