Intermediate Algebra (6th Edition)

Published by Pearson
ISBN 10: 0321785045
ISBN 13: 978-0-32178-504-6

Chapter 8 - Section 8.2 - Solving Quadratic Equations by the Quadratic Formula - Exercise Set - Page 494: 88b

Answer

94.4 million.

Work Step by Step

We use the quadratic $c(x)=-.4x^2+21x+35$ to model the number of phone wifi-enabled cellphones, in millions. To find the number projected in 2012, plug 3 into the equation. Then, simplify to find the answer: 94.4 million
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