Let x equal the age, in human years, for a dog that is 2 years old or older. For each of your chosen breeds, write an expression to model its age in dog years. [Hint: Use (x-2) in each expression.]

Question

Let x equal the age, in human years, for a dog that is 2 years old or older. For each of your chosen breeds, write an expression to model its age in dog years. [Hint: Use (x-2) in each expression.]
the dogs are
2yrs: 23 yrs old 
3yrs: 27 yrs old 
4yrs: 31 yrs old 
5yrs: 35 yrs old
I'm having trouble writing the expression's.

Steve · Answer

notice that y increases by 4 for every 1 increase in x.

So, the function will look like

y = 4x + ...

Since 4*2=8, and y(2) = 23,

y = 4x+15

Since the domain is x>=2, you could rewrite that as

y = 4(x-2) + 23