Question

A couple purchased a house in 2005. In 2009 the house appraised for $475,000. The couple refinanced the house in 2014 and the appraisal was $468,000. The couple determined a linear relationship existed between the the number of years since 2005 and the appraised value of the house.

Write a linear equation that models this relationship.

V(t) 475,000+ (475,000-468,800)

Answer 1

In thousands, let t be the number of years since 2009, since that is the year we have our first appraisal.

V(t) = 475+(468-475)/(2014-2009) t
= 475 - 1.4t

But we want t to be years since 2005. That means we have to add back 4 more years of loss: 4*1/4=5.6

V(t) = 480.6 - 1.4t
or, going back to dollars,
V(t) = 480,600 - 1400t

Answer 2

So how did you get 1.4t in this equation