Evaluate a linear function
To evaluate a function, or find a functional value, means to substitute a given value in the domain into the equation to find the corresponding element in the range.
Given f(x)=x+3, find f(2)
Plug x=2 into the function and simplify.
f(x) 
= 
x+3 


f(2) 
= 
2+3 

Plug x=2 
f(2) 
= 
5 

Simplify 