SOLUTION: A laptop computer is purchased for $1500. Its value each year is about 80% of its value in the preceding year. Its value in dollars after t years is given by the exponential functi

Algebra ->  Exponential-and-logarithmic-functions -> SOLUTION: A laptop computer is purchased for $1500. Its value each year is about 80% of its value in the preceding year. Its value in dollars after t years is given by the exponential functi      Log On


   



Question 315374: A laptop computer is purchased for $1500. Its value each year is about 80% of its value in the preceding year. Its value in dollars after t years is given by the exponential function
v(t) = 1500(0.8)^t.
a) After what amount of time will the computer's value be $900?
b) After what amount of time will the computer's value be half the original value?

Answer by josmiceli(19441) About Me  (Show Source):
You can put this solution on YOUR website!
v%28t%29+=+1500%2A.8%5Et
(a)
900+=+1500%2A.8%5Et
.8%5Et+=+.6
t%2Alog%28.8%29+=+log%28.6%29
t+=+log%28.6%29%2Flog%28.8%29
Use calculator to find t