Question

Implement a function that returns True, if any pair of numbers, x and y, in the list satisfies x=n and y=2n. Otherwise, the function should return False. Name the function doubles (1st). For example, doubles ([2,3,4] ) returns True because the list contains 2 and 4 . However, doubles ([2,3,5]) returns False.

Answer 1

The 'doubles' function checks if any number in a list has a counterpart that is double that number. It returns True if such a pair exists and False otherwise. Using a for loop, it verifies the presence of an element's double in the list.

Step-by-step explanation:

To answer the student's request, we need to implement a function called doubles that checks if there exists at least one pair of numbers (x, y) within a list such that x equals n and y equals 2n. The function should return True if such a pair is found and False otherwise. Let's create this function using a programming language like Python:

def doubles(lst): for n in lst: if n in lst and 2 * n in lst: return True return False# Test casesprint(doubles([2, 3, 4])) # Trueprint(doubles([2, 3, 5])) # False

This function iterates through each element x in the list. For each element, it checks if its double (2x) is also present in the list. If such a match is found, the function returns True. If no such pairs are found after checking all elements, the function returns False. For example, doubles([2, 3, 4]) would return True as it contains the numbers 2 and 4, which satisfy the condition x=n and y=2n. Conversely, doubles([2, 3, 5]) would return False as there are no such pairs that satisfy the condition.