Final answer:
The linear search algorithm returns 0 when searching for 1 in the given list.
Step-by-step explanation:
The linear search algorithm is used to search for a given element in a list by checking each element in the list one by one until the desired element is found or the end of the list is reached. In this case, we are searching for the value 1 in the list [1, 5, -2, 4, 3, 7, 9].
The algorithm starts by comparing the first element of the list with the desired value. Since the first element is 1, which is equal to the desired value, the algorithm immediately returns the index of the element, which is 0.
Therefore, the value returned by the linear search algorithm when searching for 1 in the list is 0.