SOLUTION: Daniel purchased a laptop for $1180 . Currently, 3 years later, the laptop is worth $805 . Assuming that the value is changing linearly, estimate the value of the laptop 4 y

Algebra ->  Finance -> SOLUTION: Daniel purchased a laptop for $1180 . Currently, 3 years later, the laptop is worth $805 . Assuming that the value is changing linearly, estimate the value of the laptop 4 y      Log On


   



Question 1093831: Daniel purchased a laptop for $1180 . Currently, 3 years later, the laptop is worth $805 .
Assuming that the value is changing linearly, estimate the value of the laptop 4 years from now (a total of 7 years after it was first bought).

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
Plot time in yrs on the horizontal axis
Plot value of the laptop on the vertical axis
Let +x+=+0+ be the time in yrs when he bought it
Use general point-slope formula
+%28+805+-+1180+%29+%2F+%28+3+-+0+%29+=+%28+y+-+1180+%29+%2F+%28+x+-+0+%29+
+%28+-375+%29+%2F+3+=+%28+y+-+1180+%29+%2F+x+
+-375x+=+3y+-+3540+
+3y+=+-375x+%2B+3540+
+y+=+-125x+%2B+1180+
--------------------------
+x+=+7+
+y+=+-125%2A7+%2B+1180+
+y+=+-875+%2B+1180+
+y+=+305+
It will be worth $305
------------------------
check:
Does equation go through ( 3, 805 ) ?
+y+=+-125x+%2B+1180+
+805+=+-125%2A3+%2B+1180+
+805+=+-375+%2B+1180+
+805+=+805+
OK