b Subtract to find the number of years since 1999, then use the equation from Part A.
A
a T = 3n+7
B
b 4900
Practice makes perfect
a We are given models for the number of hundreds of cats C and dogs D that are adopted in the United States each year after 1999. To find the total number of adoptions T, we need to add the expressions for the cats and dogs together.
Since the expression cannot be simplified any further, the function for the total number of cats and dogs adopted in hundreds is T=3n+7.
b We are asked to estimate the total number of cats and dogs that will be adopted in 2013, assuming that the trend continues. Since n represents the number of years since 1999, we first need to determine how many years 2013 is after 1999.
2013-1999=14
Now, we can substitute n=14 into the function we wrote in Part A and solve for T.
We found that when n=14, T=49. In the context of the situation and based on the trends presented, 4900 cats and dogs will be adopted in the United States in 2013.
