Answer
a) $(.8, 6)$
b) This answer means that .8 years after 2000, the number of DVD and VHS units sold was the same.
c) Please see the graph. VHS is declining while DVD is increasing in popularity.
d) -.6 billion dollars. This means that VHS sales are close to zero (if not at zero), since we can't have a negative dollar amount.
Work Step by Step
a)
$y=-1.1x+7.1$
$y=1.9x+4.7$
$-1.1x+7.1=1.9x+4.7$
$2.4=3x$
$2.4/3 = 3x/3$
$.8 = x$
$y=-1.1x+7.1$
$y=-1.1*.8+7.1$
$y=-.88+7.1$
$y=6.22$
c)
Red line: $y=-1.1x+7.1$
Blue line: $y=1.9x+4.7$
d)
$2007-2000=7$
$y=-1.1x+7.1$
$y=-1.1*7+7.1$
$y=-7.7+7.1$
$y=-.6$
