I think the largest time interval over which the actual price per watt of a solar panel was an increasing function of time is : 2004 to 2006
As it gives data %growth over previous year
from 2003 to 2004 it was -5.7% but from 2004 to 2005 6.7 % from 2005 to 2006 it is 97 % and from there it once again decline
hope this helps
Answer:
Only one solution 
Step-by-step explanation:

Multiply equation
by 

Now from equation 
equation

Put the value in equation 

hence only one solution exists
.
Step-by-step explanation:
Now, assuming is a vertical parabola, so the squared variable is the "x", let's do some checking.