Mathematics 2009 JAMB Past Questions - Question 10: If x = { n² + 1: n is a positive integer and 1≤ n ≤ 5 } , Y = { 5n : n is a positive integer and 1≤ n ≤ 5 }, find x ᴖ y.

Correct Answer

A

Explanation

x = {2,5,10,17,26} y= {5,10,15,20,25} = xᴖy = {5,10}To find the intersection (ᴖ) of sets x and y, we need to identify the elements that are common to both sets.Set x consists of the values obtained by squaring a positive integer n and adding 1, where n is between 1 and 5 (inclusive). So, x = {2² + 1, 3² + 1, 4² + 1, 5² + 1} = {5, 10, 17, 26}.Set y consists of the values obtained by multiplying a positive integer n by 5, where n is between 1 and 5 (inclusive). So, y = {5 * 1, 5 * 2, 5 * 3, 5 * 4, 5 * 5} = {5, 10, 15, 20, 25}.To find the intersection of x and y, we identify the common elements in both sets:x ᴖ y = {5, 10}Therefore, the intersection of sets x and y is {5, 10}.