Exams › JEE Main › Maths

Given x - y = 2 and x*y = 24, find the value of 1/x + 1/y.

1. 1/12
2. -1/12
3. 1/6
4. 2/24

Correct answer: 1/12

Solution

We need (x + y)/(x*y). From x - y = 2 and xy = 24: (x + y)² = (x - y)² + 4xy = 4 + 96 = 100, so x + y = 10 (taking the positive value; e.g. x = 6, y = 4). Then 1/x + 1/y = (x + y)/(xy) = 10/24 = 5/12. Hmm 10/24 = 5/12, not 1/12. Recheck: with x=6,y=4: 1/6+1/4 = 2/12+3/12 = 5/12. So correct value is 5/12.

Related JEE Main Maths questions

• Let A be the set {(n, 2n): n ∈ N} and let B be the set {(2n, 3n): n ∈ N}. What is the intersection A ∩ B?
• Let set A contain 3 elements and set B contain 6 elements. Then the cardinality of their union must satisfy
• Given the sets A = {1, 2, 5} and B = {3, 4, 5, 9}, what is A ∩ B?
• At a conference with 100 attendees, 29 are Indian women and 23 are Indian men. Among the Indian attendees, 4 are doctors, and 24 are either men or doctors. If there are no foreign doctors, how many foreigners and how many women doctors are present at the conference?
• Let X and Y be two non-empty sets, and let A be a non-empty set such that X ∩ A = Y ∩ A = A and X ∪ A = Y ∪ A. Which of the following must be true?
• If A and B are non-empty sets with A containing B, then which of the following is true?

⚔️ Practice JEE Main Maths free + battle 1v1 →