Learning Resources

Investigation 1: Total Earnings & Focus A: Combination by Subtraction

In Investigation 1, you saw that the domain of functions being combined must be equal. Recall that the same working hours were required for each of Darcy's jobs in order to combine the functions f(x) and g(x). 

In focus A, values for h(x) and k(x) can only be combined when there is a value for both f(x) and g(x). Hence, in the table of values for f(x), you must ignore the x-value of 4 since it is not in the domain of g(x). Likewise, you discard the ordered pair (-3,20) in the table for g(x).